Question

A grocery store receipts show that Sunday customer purchases have a skewed distribution with a mean of $35 and a standard deviation of $23. Suppose the store had 324 customers this Sunday

A) Estimate the probability that the store's revenues were at least $12,200?

B) If, on a typical Sunday, the store serves 324 customers, how much does the store take in on the worst 10% of such days?

Answer 1

From the given data

The mean for sample mean

  

Standard deviation of the distribution of sample mean

(a)

Probability that the stores revenues were at least is

  

By using the normal distribution table

we get the value

(b)

given worst 10% such days

By using standard normal distribution table, the indicated Z-score for the area of 0.10 is = -1.28

So