Question

At a store, customers are randomly selected to participate in a survey.

On Friday, there were 500 customers at the store. Of those, 90 were
selected to participate in the survey. On Saturday, the store manager
wants 126 people to participate in the survey.
Part A: If the probability of being selected to participate in the survey
on Saturday is the same as it was on Friday, how many total
customers must enter the store on Saturday?
Part B: If 25% of the customers who completed the survey were
female, how many total females completed the survey?

Answer 1

For the probability and percentage:

• 700 customers must enter the store on Saturday to maintain the same probability of selection as Friday.
• 22 females completed the survey.

How to solve probability?

Part A:

On Friday, the probability of being selected to participate in the survey was 90 / 500 = 0.18.

If the probability of being selected on Saturday is the same as it was on Friday, set up a proportion:

0.18 = 126 / x

where x = total number of customers needed on Saturday.

Solving for x,:

x = 126 / 0.18

= 700 customers

Therefore, 700 customers must enter the store on Saturday.

Part B:

25% of the customers who completed the survey were female. If 90 customers completed the survey, then:

25% × 90 = 22.5 females

Therefore, 22 females completed the survey