Confused on how to solve

Question

Let x₁, x₂, . . . , x₁₀₀ denote the actual net weights (in pounds) of 100 randomly selected bags of fertilizer. Suppose that the weight of a randomly selected bag has a distribution with mean 25 lbs and variance 1 lb². Let x be the sample mean weight (n = 100).

What is the probability that the sample mean is between 24.75 lbs and 25.25 lbs? (Round your answer to four decimal places.)

P(24.75 ≤ x ≤ 25.25) = .9876

What is the probability that the sample mean is greater than 25 lbs?

??? Confused on how to solve it as I did 1-.9876 but it still was wrong ???

Answer 1

Hi Michael,

When you took 1 - .9876, that includes both ends--the area below 24.75 and above 25.25. You need to divide that probability by 2 to get greater side only.

P = (1 -0.9876)/2

P = 0.0062

I hope this helps.