Question

The sales data from the past two months of a frozen yogurt shop are approximately normal.

The mean daily sales for the first month was $200 with a standard deviation of $30. On the 15th of the first month, the shop sold $245 of yogurt.

The mean daily sales for the second month was $220 with a standard deviation of $50. On the 15th of the second month, the shop sold $270 of yogurt.

Which month had a higher z-score for sales on the 15th, and what is the value of that z-score?

Answer 1

To find out which month had a higher z-score for sales on the 15th, we need to calculate the z-score for each month using the given information.

For the first month, we have:

mean = $200

standard deviation = $30

sales on the 15th = $245

z-score = (245 - 200) / 30 = 1.5

For the second month, we have:

mean = $220

standard deviation = $50

sales on the 15th = $270

z-score = (270 - 220) / 50 = 1

Therefore, the second month had a higher z-score for sales on the 15th, with a value of 1.