The manager of a sandwich shop wants to change the hours the shop closes. he needs to decide who to survey next week. which description would be an unbiased sample? a. every costumer who places an order greater than $20 throughout the week b. all customers who come into the shop before noon each day c. the last 10 customers at the end of each day, or d, every fifth customer throughout the week.

D, every fifth customer throughout the week.

If a  manager of a sandwich shop wants to change the hours the shop closes and needs to decide who to survey for his plan,  an unbiased sample to use is D, every fifth customer throughout the week.

It is an unbiased sample because it is a simple random sampling in which every fifth customer throughout the week, has an equal probability of being chosen, regardless of how much his order, the time he comes into the shop.  

30 feet

step-by-step explanation:

that would be 2 1/2 * 12

= 24 + 6

= 30 feet   (answer)