Unit 8 Test Review (Probability)

How many people did not attend the school play?

Mathematical Equivalence

ON

Out of those surveyed, what is the probability that the student is a boy who can't bike to school?

• 4/30

• 7/30

• 2/15

• 14/30

Answer explanation

The probability of a boy who can't bike to school is 4 out of 30 surveyed students, so the correct answer is 4/30.

Looking at the girls surveyed, what's the probability that they speak French? 

• 2.14

• .24

• .4

• .8571

Answer explanation

There were 30 girls surveyed, 12 of them speak french, so the probability is 12/30 or .40 or 40%

Determine whether the question would be a permutation or combination: Five students from 90 will be selected to count ballots for the Class President election. How many groups of 5 students could be selected to count ballots?

• Permutation

• Combination

• Neither

Answer explanation

The question involves selecting a group of students from a larger set, which aligns with the concept of combinations, not permutations. Therefore, the correct choice is Combination.

What does ₁₀P₅ mean?

• Permutations with 5 choices and 10 positions

• Permutations with 10 choices and 5 positions

• Permutations with 5 numbers and 10 operations

• Permutations with 5 hot dogs and 10 drinks

Determine whether the following scenarios are a permutation or a combination:
 
Selecting a lead and an understudy for a school play.

• Combination

• Permutation

Answer explanation

Selecting a lead and an understudy involves arranging two distinct roles, making it a permutation as order matters in this scenario.

The ski club with ten members is to choose three officers for captain, co-captain and secretary.  How many ways can those offices be filled?

• 720

• 120

• 10!

Answer explanation

This is a permutation problem because we are filling specific roles.

The permutation formula is nPr = n!/(n-r)!

which is 10! / (10-3)! = 720.

There are 18 people running in a cross country race. How many possible ways are there to place the runners in first, second, and third?

• 324

• 4,896

• 816

• 54

Answer explanation

There are 18 choices for the first place, 17 for the second, and 16 for the third. Multiply these together to get 18*17*16 = 4,896 possible ways to place the runners.

OR

You can use the permutation formula since the order matters in this problem nPr = n!/(n-r)! = 18!/(18-3)! = 4896

What is the probability of the spinner landing on yellow?

Answer explanation

There is 1 yellow section out of 4 equal sections, so the correct answer is 1/4.

What is the probability of randomly picking a Purple marble from Molly's Sack of Marbles?

Answer explanation

There are 2 purple marbles out of the total 15 marbles in the sack, so the correct answer is 2/15.