Question

Let the random variable X represent the profit made on a randomly selected day by a certain store. Assume that X is normal with a mean $360 and a standard deviation of $50. What is the value of P(X>$400)?

a. 0.2119
b. 0.2881
c. 0.7881
d. 0.8450
e. the answer cannot be computed

Answer 1

Hi there

Answer 2

hey

Answer 3

Determine how many standard deviations above the mean 400 is, then check a Z-score chart for the normal distribution

Answer 4

thanks!

Answer 5

Remember the z-score chart tells you the mass of the curve to the left, but the problem is asking for the area of the curve to the right of 400, so you'll have to take the complement of the value you find in the chart (i.e. 1 minus the value you find)

Answer 6

got it!