Probability Worksheets

**Page 1**

1.

Find the probability of scoring more than 8 when two dice are rolled.

a. | 0.34 | ||

b. | 0.45 | ||

c. | 0.62 | ||

d. | 0.28 |

[The 10 favorable outcomes are (3, 6), (4, 5), (5, 4), (6, 3), (5, 5), (4, 6), (6, 4), (5, 6), (6, 5) and (6, 6).]

Number of possible outcomes = Total number of outcomes when two dice are rolled = 36

P(more than 8) =

=

[Substitute and simplify.]

The probability of scoring more than 8 is 0.28.

Correct answer : (4)

2.

Are the two events dependent or independent?

1. Drawing a king from a pack of cards without replacing it.

2. Again drawing another king.

1. Drawing a king from a pack of cards without replacing it.

2. Again drawing another king.

a. | Independent | ||

b. | Dependent |

The number of kings in the pack of cards and the total number of cards is reduced by one, if the previously drawn king is not replaced back.

The probability of drawing a king for the second time is different from the previous draw and is dependent on the previous draw.

The happening of one event is affecting the happening of the other.

So, the two events are dependent.

Correct answer : (2)

3.

Are the two events dependent or independent?

1. Tossing a coin.

2. Rolling a dice.

1. Tossing a coin.

2. Rolling a dice.

a. | Independent | ||

b. | Dependent |

This is because, tossing a coin is totally different event from rolling a dice.

The happening of one event is not affecting the happening of the other.

So, the two events are independent.

Correct answer : (1)

4.

Nathan rolls a fair die 2 times. Find the probability that he rolls all 6's.

a. | 0.00277 | ||

b. | 0.02777 | ||

c. | 2.77700 | ||

d. | 2.77700 |

The probability of rolling the number 6 all the 2 times = (

[Use multiplication principle of probability.]

Correct answer : (2)

5.

Which of the following could not be the probability of an event ?

a. | 0.96 | ||

b. | 0.0001 | ||

c. | $\frac{2}{e}$ | ||

d. | $\frac{e}{2}$ |

Among the choices

[

Correct answer : (4)

6.

Ashley has 6 dollars, 4 nickels and 8 dimes in her purse. What is the probability of selecting a dime from her purse?

a. | 1 | ||

b. | $\frac{8}{9}$ | ||

c. | $\frac{1}{18}$ | ||

d. | $\frac{4}{9}$ |

Number of possible outcomes = Total number of coins = 18

=

P(dime) =

Probability of selecting a dime is

Correct answer : (4)

7.

Out of 70 plants, 20 had yellow flowers and 50 had violet flowers. Find the probability of choosing a plant with violet flowers.

a. | $\frac{1}{7}$ | ||

b. | $\frac{5}{7}$ | ||

c. | $\frac{4}{5}$ | ||

d. | None of the above |

Number of possible outcomes = Total number of plants = 70

P(violet) =

=

[Substitute and simplify.]

The probability of choosing a plant with violet flowers is

Correct answer : (2)

8.

There are 20 paddle boats, 15 boats with oars and 25 motorboats in a boat club. If a boat is chosen at random, what is the probability of not selecting a paddle boat?

a. | $\frac{2}{3}$ | ||

b. | $\frac{21}{61}$ | ||

c. | $\frac{1}{60}$ | ||

d. | $\frac{3}{11}$ |

Total number of boats = 20 + 15 + 25 = 60

[Add the values.]

Probability of selecting a paddle boat is 20 out of 60 =

[Simplify.]

P(no paddle boat) = 1 -

[Substitute and subtract.]

The probability of not selecting a paddle boat is

Correct answer : (1)

9.

A card is drawn from a deck of 52 cards. What is the probability that it is a digit card?

a. | $\frac{9}{13}$ | ||

b. | $\frac{9}{11}$ | ||

c. | $\frac{1}{52}$ | ||

d. | $\frac{1}{13}$ |

There will be a total of 16 non-digit cards in the deck of playing cards.

Number of digit cards in the deck of cards = Total number of cards in the deck of cards - Number of non-digit cards = 52 - 16 = 36

[Substitute and subtract.]

Number of favorable outcomes = Number of digit cards = 36

Number of possible outcomes = Total number of cards = 52

P(digit card) =

[Substitute and simplify.]

The probability that the card drawn is a digit card is

Correct answer : (1)

10.

A card is drawn from a standard deck of cards. What are the odds in favor of drawing a spade?

a. | $\frac{1}{39}$ | ||

b. | $\frac{1}{3}$ | ||

c. | $\frac{3}{4}$ | ||

d. | $\frac{1}{12}$ |

Number of unfavorable outcomes = Number of cards other than spades = 39

[Since 52 - 13 = 39.]

Odds in favor of an event =

[Substitute and simplify.]

Odds in favor of drawing a spade is

Correct answer : (2)