Solutions: Probability

Introduction to Probability

Exercise Trouble Solution
1 Which of the following is an experiment?

Tossing a coin.
Rolling a single half-dozen-sided die.
Choosing a marble from a jar.
All of the higher up.

All of the higher up.
two Which of the following is an upshot?

Rolling a pair of die.
Landing on carmine.
Choosing 2 marbles from a jar.
None of the higher up.

Landing on reddish.
3 Which of the following experiments does NOT accept every bit likely outcomes?

Choose a number at random from 1 to seven.
Toss a coin.
Choose a letter at random from the give-and-take School.
None of the above.

Cull a letter at random from the give-and-take School (Schoolhouse has 2 O's).
4 What is the probability of choosing a vowel from the alphabet?

21_over_26.gif

5_over_26.gif

1_over_21.gif

None of the above.

5_over_26.gif
5 A number from 1 to eleven is chosen at random. What is the probability of choosing an odd number?

1_over_11.gif

5_over_11.gif

6_over_11.gif

None of the to a higher place.

6_over_11.gif

Sure and Incommunicable Events

Exercise Problem Solution
1 A glass jar contains five red, 3 blue and two green jelly beans. If a jelly bean is chosen at random from the jar, then which of the post-obit is an incommunicable event?

Choosing a blood-red jelly bean.
Choosing a bluish jelly bean.
Choosing a yellow jelly bean.
None of the above.

Choosing a yellow jelly bean.
2 A spinner has 7 equal sectors numbered i to 7. If you spin the spinner, and then which of the following is a sure issue?

Landing on a number less than seven.
Landing on a number less than eight.
Landing on a number greater than i.
None of the above.

Landing on a number less than 8
3 What is the probability of choosing 14 hearts from a standard deck of 52 playing cards?

14_over_52.gif

one

0

None of the above.

0; Each suit has only 13 cards.
4 If a number is chosen at random from the following list, then what is the probability that information technology is prime?
ii, iii, 5, 7, eleven, 13, 17, nineteen

1

0

1_over_8.gif

None of the in a higher place.

1
5 If a single six-sided die is rolled, so which of the post-obit events is neither certain nor impossible?

Rolling a number less than 7.
Rolling an fifty-fifty number.
Rolling a zero.
None of the above.

Rolling an fifty-fifty number.

Sample Spaces

Do Problem Solution
ane What is the sample space for choosing an odd number from one to eleven at random?

i, 2, 3, 4, v, 6, 7, 8, 9, 10, 11
{1, 2, 3, 4, five, half dozen, 7, eight, 9, 10, 11}
{ane, 3, 5, 7, 9 11}
None of the above.

{1, 3, 5, 7, 9 xi}
2 What is the sample space for choosing a prime number less than 15 at random?

{two, three, 5, vii, 11, 13, 15}
{ii, 3, 5, vii, 11, thirteen}
{2, 3, five, 7, 9, 11, 13}
All of the above.

{2, 3, 5, vii, xi, 13}
3 What is the sample space for choosing 1 jelly bean at random from a jar containing 5 cherry, 7 blue and 2 green jelly beans?

{5, 7, 2}
{5 scarlet, 7 blueish, ii green}
{red, blue, green}
None of the above.

{red, blueish, green}
4 What is the sample infinite for choosing one letter of the alphabet at random from 5 vowels?

{a, e, i, o, u}
{v, o, due west, e, l}
{1, 2, iii, 4, five}
None of the to a higher place.

{a, eastward, i, o, u}
5 What is the sample space for choosing i letter of the alphabet at random from the word DIVIDE?

{d, i, 5, i, d, eastward}
{i, 2, three, four, 5, six}
{d, i, 5, due east}
None of the above.

{d, i, five, e}

The Complement of an Result

Practice Problem Solution
1 A glass jar contains five red, 3 bluish and two green jelly beans. If a jelly bean is chosen at random from the jar, what is the probability that information technology is not blueish?

1_over_2.gif

3_over_10.gif

7_over_10.gif

None of the above.

1 - 3_over_10.gif = 7_over_10.gif

Answer: 7_over_10.gif

2 A pupil is chosen at random from a grade of xvi girls and fourteen boys. What is the probability that the educatee chosen is non a girl?

8_over_15.gif

7_over_15.gif

1

None of the above.

i - 16_over_30.gif = 14_over_30.gif = 7_over_15.gif

Answer: 7_over_15.gif

3 A number from 1 to five is chosen at random. What is the probability that the number chosen is not odd?

2_over_5.gif

3_over_5.gif

0

None of the above.

1 - 3_over_5.gif = 2_over_5.gif

Answer: 2_over_5.gif

four If a number is chosen at random from the post-obit list, what is the probability that it is not prime number?
ii, 3, 5, vii, 11, xiii, 17, 19

1

1_over_8.gif

0

None of the above.

1 - 8_over_8.gif = 0

Answer: 0 (this is an impossible event)

v If a single 6-sided dice is rolled, what is the probability of rolling a number that is not eight?

5_over_6.gif

one

0

None of the above.

P(eight) = 0; P(not eight) = 1 - 0 = 1

Answer: 1 (This is a certain outcome)

Mutually Exclusive Events

Do Problem Solution
1 Which of the following are mutually exclusive events when a single carte du jour is called at random from a standard deck of 52 playing cards?

Choosing a 7 or Choosing a club.
Choosing a vii or Choosing a jack.
Choosing a 7 or Choosing a middle.
None of the higher up.

Choosing a 7 or Choosing a jack
2 All of the following are mutually exclusive events when a unmarried 6-sided die is rolled EXCEPT:

Rolling a number less than 4 or Rolling a number greater than 4.
Rolling a 2 or Rolling an odd number.
Rolling a ii or Rolling an even number.
None of the above.

Rolling a two or Rolling an even number.
iii Which of the following are mutually exclusive events when a solar day of the week is chosen at random?

Choosing a Mon or Choosing a Wednesday.
Choosing a Sabbatum or Choosing a Sun.
Choosing a weekday or Choosing a weekend day.
All of the above.

All of the above.
4 A single letter is chosen at random from the word Instructor. All of the following are mutually exclusive events except:

Choosing a T or Choosing a consonant.
Choosing a T or Choosing a vowel.
Choosing an E or Choosing a C.
None of the above.

Choosing a T or Choosing a consonant.
5 Which of the following are mutually exclusive events when a month of the yr is chosen at random?

Choosing Baronial or Choosing a summer month.
Choosing September or Choosing a autumn month.
Choosing a summertime month or Choosing a wintertime month.
None of the higher up.

Choosing a summer month or Choosing a winter month.

Improver Rules for Probability

Practice Problem Solution
1 A day of the week is chosen at random. What is the probability of choosing a Mon or Tuesday?

1_over_7.gif

2_over_14.gif

2_over_7.gif

None of the above.

1_over_7.gif + 1_over_7.gif = 2_over_7.gif

Answer: 2_over_7.gif

2 In a pet store, there are 6 puppies, ix kittens, 4 gerbils, and 7 parakeets. If a pet is chosen at random, what is the probability of getting a puppy or a parakeet?

1_and_15_over_26.gif

1_over_2.gif

11_over_26.gif

None of the to a higher place.

6_over_26.gif + 7_over_26.gif = 13_over_26.gif = 1_over_2.gif

Answer: 1_over_2.gif

3 The probability of a New York teenager owning a skateboard is 0.37, of owning a wheel is 0.81, and of owning both is 0.36. If a New York teenager is called at random, what is the probability that the teenager owns a skateboard or a bicycle?

1.18
0.7
0.82
None of the above.

(0.37 + 0.81) - 0.36 = 0.82

Reply: 0.82

4 A number from 1 to ten is chosen at random. What is the probability of choosing a 5 or an even number?

3_over_5.gif

1_over_2.gif

1_over_5.gif

All of the above.

P(5) = 1_over_10.gif

P(even) = 5_over_10.gif

P(5 or even) = 1_over_10.gif + 5_over_10.gif= 6_over_10.gif = 3_over_5.gif

Respond: 3_over_5.gif

five A single 6-sided die is rolled. What is the probability of rolling a number greater than three or an even number?

1

2_over_3.gif

5_over_6.gif

None of the above.

P(greater than 3) = 3_over_6.gif

P(fifty-fifty) = 3_over_6.gif

P(both) = 2_over_6.gif

P(greater than three AND even)

= (3_over_6.gif + 3_over_6.gif) - 2_over_6.gif = 4_over_6.gif = 2_over_3.gif

Answer: 2_over_3.gif

Probability of Independent Events

Exercise Problem Solution
1 Spin a spinner numbered 1 to vii, and toss a money. What is the probability of getting an odd number on the spinner and a tail on the coin?

3_over_14.gif

2_over_7.gif

5_over_14.gif

None of the to a higher place.

4_over_7.gif · 1_over_2.gif = 4_over_14.gif = 2_over_7.gif

Answer: 2_over_7.gif

ii A jar contains half dozen ruby balls, iii green assurance, 5 white assurance and vii xanthous assurance. Two assurance are chosen from the jar, with replacement. What is the probability that both balls are green?

6_over_441.gif

2_over_49.gif

1_over_49.gif

None of the above.

3_over_21.gif · 3_over_21.gif = 9_over_441.gif = 1_over_49.gif

Answer: 1_over_49.gif

3 In Do two, what is the probability of getting a reddish and a yellow brawl?

2_over_21.gif

3_over_21.gif

13_over_63.gif

All of the above.

6_over_21.gif · 7_over_21.gif = 42_over_441.gif

= 2_over_21.gif

Respond: 2_over_21.gif

4 4 cards are called from a standard deck of 52 playing cards with replacement. What is the probability of choosing 4 hearts in a row?

13_over_52.gif

1_over_16.gif

1_over_256.gif

None of the in a higher place.

13_over_52_0.gif · 13_over_52_0.gif · 13_over_52_0.gif · 13_over_52_0.gif

1_over_4.gif · 1_over_4.gif · 1_over_4.gif · 1_over_4.gif

= 1_over_256.gif

Reply: 1_over_256.gif

5 A nationwide survey showed that 65% of all children in the U.s. dislike eating vegetables. If 4 children are chosen at random, what is the probability that all 4 dislike eating vegetables? (Round your answer to the nearest percent.)

18%
260%
2%
None of the above.

65% = .65;

(.65)(.65)(.65)(.65)

= .179

.179 rounded to the nearest percent is eighteen%

Reply: 18%

Probability of Dependent Events

Practice Problem Solution
one Two cards are chosen at random from a deck of 52 cards without replacement. What is the probability of getting two kings?

4_over_663.gif

1_over_221.gif

1_over_69.gif

None of the in a higher place.

4_over_52a.gif · 3_over_51.gif = 12_over_2652.gif

= 1_over_221.gif

Reply: 1_over_221.gif

2 Ii cards are chosen at random from a deck of 52 cards without replacement. What is the probability that the first menu is a jack and the 2nd card is a ten?

3_over_676.gif

1_over_169.gif

4_over_663_1.gif

None of the to a higher place.

4_over_52a.gif · 4_over_51.gif = 16_over_2652.gif

= 4_over_663_1.gif

Reply: 4_over_663_1.gif

3 On a math test, 5 out of xx students got an A. If three students are called at random without replacement, what is the probability that all three got an A on the test?

1_over_114.gif

25_over_1368.gif

3_over_400.gif

None of the above.

5_over_20.gif · 4_over_19.gif · 3_over_18.gif =

60_over_6840.gif = 1_over_114.gif

Answer: 1_over_114.gif

4 Three cards are called at random from a deck of 52 cards without replacement. What is the probability of getting an ace, a rex and a queen in order?

1_over_2197.gif

8_over_5525.gif

8_over_16575.gif

None of the higher up.

P(ace, male monarch, queen)

= 4_over_52a.gif · 4_over_51.gif · 4_over_50.gif

64_over_132600.gif = 8_over_16575_1.gif

Answer: 8_over_16575_1.gif

5 A school survey found that 7 out of 30 students walk to school. If iv students are selected at random without replacement, what is the probability that all four walk to school?

343_over_93960.gif

1_over_783.gif

7_over_6750.gif

None of the above.

7_over_30.gif · 6_over_29.gif · 5_over_28.gif · 4_over_27.gif =

840_over_657720.gif = 1_over_783.gif

Respond: 1_over_783.gif

Conditional Probability

Exercise Problem Solution
1 In New York State, 48% of all teenagers own a skateboard and 39% of all teenagers own a skateboard and rollerblades. What is the probability that a teenager owns rollerblades given that the teenager owns a skateboard?

87%
81%
123%
None of the above.

point39_over_point48.gif = .8125

Answer: 81% (to the nearest percent)

2 At a heart school, 18% of all students play football and basketball, and 32% of all students play football game. What is the probability that a educatee plays basketball given that the pupil plays football game?

56%
178%
fifty%
None of the higher up.

point18_over_point32.gif = .5625

Answer: 56% (to the nearest pct)

3 In the United States, 56% of all children get an assart and 41% of all children get an allowance and do household chores. What is the probability that a child does household chores given that the child gets an allowance?

137%
97%
73%
None of the above.

point41_over_point56.gif = .7321

Answer: 73% (to the nearest percentage)

four In Europe, 88% of all households take a telly. If information technology is known that 51% of all households accept a VCR given that they also accept a television, then what is the probability that a household has a VCR and a television?

58%
45%
173%
None of the in a higher place.

Allow A denote the event "have a idiot box" and let B denote the consequence "take a VCR".

conditional_soln_exercise4_step1.gif

conditional_soln_exercise4_step2.gif

conditional_soln_exercise4_step3.gif

Respond: 45% (to the nearest percent)

5 In New England, 84% of the houses have a garage and 65% of the houses have a garage and a dorsum yard. What is the probability that a house has a backyard given that it has a garage?

77%
109%
nineteen%
None of the above.

point65_over_point84.gif = .7738

Answer: 77% (to the nearest percent)

Practice Exercises

Practise Problem Solution
1 Which of the following is an impossible event?

Choosing an odd number from one to x.
Getting an even number after rolling a single 6-sided die.
Choosing a white marble from a jar of 25 green marbles.
None of the above.

Choosing a white marble from a jar of 25 green marbles.
ii Which of the following is the sample space for choosing a letter from the word LIBRARY?

{I, A}
{Fifty, I, B, R, A, R, Y}
{L, I, B, R, A, Y}
None of the in a higher place.

{L, I, B, R, A, Y}
3 What is the probability that a single card chosen from a deck is non an ace?

4_over_52.gif

48_over_52.gif

39_over_52.gif

None of the above.

P(not ace) = 1 - P(ace)

= one - 4_over_52a.gif

= 48_over_52_0.gif

Answer: 48_over_52_0.gif

4 Which of the following is a certain outcome?

Choosing a teacher from a room full of students.
Choosing an odd number from the numbers 1 to 10.
Getting a 4 after rolling a single 6-sided die.
None of the above.

The probability of a certain effect is equal to one.

Respond: None of the higher up.

5 There are four parents, 3 students and 6 teachers in a room. If a person is selected at random, what is the probability that it is a instructor or a student?

9_over_13.gif

4_over_13.gif

7_over_13.gif

None of the above.

P(teacher or educatee) = P(instructor) + P(student)

= 6_over_13.gif + 3_over_13.gif

= 9_over_13_0.gif

Answer: 9_over_13_0.gif

6 In a high school computer course there are 15 juniors and 10 seniors. Four juniors and v seniors are boys. If a student is selected at random, then what is the probability of selecting a junior or a male child?

24_over_25.gif

four_fifths.gif

1_over_5.gif

None of the above.

P(junior or boy)

= P(junior) + P(male child) - P(junior and boy)

= 15_over_25.gif + 9_over_25.gif - 4_over_25.gif

= 20_over_25.gif = four_fifths.gif

Reply: four_fifths.gif

7 A jar contains 5 red, 3 green, ii imperial and 4 yellow marbles. A marble is chosen at random from the jar. Afterward replacing information technology, a second marble is chosen. What is the probability of choosing a majestic so a red marble?

5_over_98_1.gif

1_over_2_1.gif

3_over_98.gif

2_over_49_1.gif

P(majestic, cherry) = P(purple) · P(cerise)

= 2_over_14_1.gif · 5_over_14_1.gif

= 10_over_196.gif

= 5_over_98_1.gif

Respond: 5_over_98_1.gif

8 3 cards are called at random from a deck without replacement. What is the probability of choosing an eight, a seven and a 6, in order?

6_over_35152.gif

1_over_2197_1.gif

8_over_16575_2.gif

None of the to a higher place.

P(viii, 7, six)

= 4_over_52a.gif · 4_over_51.gif · 4_over_50.gif

= 64_over_132600.gif

= 8_over_16575_2.gif

Respond: 8_over_16575_2.gif

9 In a shipment of 25 DVD Players, 2 are defective. If ii DVD Players are randomly selected and tested, what is the probability that both are defective if the first one is not replaced later on it has been tested?

4_over_625.gif

1_over_300.gif

2_over_625.gif

None of the above.

P(defective, defective)

= 2_over_25.gif · 1_over_24.gif

= 2_over_600.gif

= 1_over_300.gif

Answer: 1_over_300.gif

x In a school, 48% of the students take a foreign language class and 19% of students accept both foreign linguistic communication and technology. What is the probability that a student takes applied science given that the students takes foreign language? (Circular your answer to the nearest percent.)

67%
253%
40%
None of the above.

Let FL represent foreign language

foreign_language.gif

= point19_over_point48.gif

= 0.3958333...

= 40% rounded to the nearest percent

Answer: forty%

Challenge Exercises

Exercise Problem Solution
one Which of the following is the sample space when ii coins are tossed?

{H, T, H, T}
{H, T}
{HH, HT, TH, TT}
None of the above.

{HH, HT, Thursday, TT}
2 At Kennedy Eye School, three out of v students brand honor roll. What is the probability that a student does non make award coil?

65%
xl%
60%
None of the higher up.

3_over_5_1.gif = .60; 1 - .threescore = .40

Reply: 40%

3 A large basket of fruit contains 3 oranges, ii apples and 5 bananas. If a piece of fruit is chosen at random, what is the probability of getting an orange or a banana?

4_over_5_1.gif

1_over_2_1.gif

7_over_10_1.gif

None of the in a higher place.

P(orange or banana)

= 3_over_10_1.gif + 5_over_10_1.gif

= 8_over_10.gif = 4_over_5_1.gif

Reply: 4_over_5_1.gif

4 A pair of dice is rolled. What is the probability of getting a sum of 2?

1_over_6.gif

1_over_3.gif

1_over_36.gif

None of the above.

P(1 and 1) = 1_over_6.gif · 1_over_6.gif

= 1_over_36.gif

Reply: 1_over_36.gif

5 In a course of 30 students, there are 17 girls and 13 boys. Five are A students, and three of these students are girls. If a pupil is chosen at random, what is the probability of choosing a girl or an A student?

19_over_30.gif

11_over_15.gif

17_over_180.gif

None of the above.

P(girl) + P(A) - P(girls and A)

= 17_over_30.gif + 5_over_30.gif - 3_over_30.gif

= 19_over_30.gif

Respond: 19_over_30.gif

6 In the United States, 43% of people wear a seat chugalug while driving. If 2 people are called at random, what is the probability that both of them clothing a seat belt?

86%
18%
57%
None of the higher up.

(.43)(.43) = .1849

Answer: 18% (to the nearest percent)

7 Three cards are called at random from a deck without replacement. What is the probability of getting a jack, a ten and a ix in lodge?

8_over_16575_2.gif

1_over_2197_1.gif

6_over_35152.gif

None of the above.

P(jack, 10, nine)

solns_challenge7_step1.gif

8_over_16575_2.gif

Answer: 8_over_16575_2.gif

viii A city survey constitute that 25% of teenagers accept a function time chore. The same survey establish that twoscore% plan to attend college. If a teenager is chosen at random, what is the probability that the teenager has a part fourth dimension job and plans to attend college?

65%
fifteen%
10%
None of the in a higher place.

(.25)(.40) = .x

Answer: x%

ix In a school, xiv% of students have drama and computer classes, and 67% take drama class. What is the probability that a student takes computer class given that the student takes drama class?

81%
21%
53%
None of the above.

= .2090

Reply: 21% (to the nearest percentage)

x In a shipment of 100 televisions, half-dozen are defective. If a person buys 2 televisions from that shipment, what is the probability that both are defective?

3_over_100.gif

9_over_2500.gif

1_over_330.gif

None of the in a higher place.

P(defective, defective)

= 6_over_100.gif · 5_over_99.gif

= 30_over_9900.gif

= 1_over_330.gif

Reply: 1_over_330.gif

IXL