4.92 A food truck owner, Ayesha, sells each roll for €2.50.

She finds that 70% of her customers prefer chicken rolls.

Suppose she makes a random selection of 8 customers.

State at the outset what assumption she has made.

a. Find the probability that at least 2 customers prefer chicken rolls.

b. Find the probability that exactly 6 customers prefer chicken rolls.

c. Find the mean and standard deviation of the number of customers who prefer chicken rolls.

d. Find the mean and standard deviation of the total number of chicken rolls she sells.