Question

Kroger runs Buy One Get One (BOGO) promotions every year to promote charcoal for Memorial Day. Their data indicates that 76 customers per day per store purchase this deal every spring and the standard deviation historically is 12 customers. Assume that the population is normally distributed. What is the probability that for a random sample of 15 days, at least 70 customers per day will buy charcoal with the BOGO?

1) 0.6915

2) 0.9772

3) 0.0262

4)0.9738

Answer 1

Solution :

Given that ,

mean = = 76 customers

standard deviation = = 12 customers

n = 15

=    = 76 customers

= / n = 12 / 15 = 3.10

P( > 70) = 1 - P( < 70)

= 1 - P[( - ) / < (70 - 76) / 3.10]

= 1 - P(z < -1.94)

Using z table,    

= 1 - 0.0262

= 0.9738

correct option is = 4.