Question

The weights of cockroaches follow a Normal distribution with mean 80 grams and standard deviation 2 grams. Use normal table to answer the question below:

What percent of cockroaches weigh greater than 85 grams?

Answer 1

Answer:

0.621%

Step-by-step explanation:

First of all let's find the z-score which is given by the formula;

z = (x' - μ)/σ

We are given;

Mean; μ = 80 g

Standard deviation; σ = 2 g

Test score; x' = 85 g

Thus;

z = (85 - 80)/2

z = 5/2

z = 2.5

From the z-distribution table attached, at z = 2.5, the probability is:

P(z > 2.5) = 1 - 0.99379 = 0.00621 or 0.621%