Question

The mean weight of a litter of kittens is 3.1 pounds, with a standard deviation of 0.9 pound. Lawrence wants to know the weight of the kitten he is buying, but the seller only has the z-score of 1.22. How much does the kitten weigh?

Answer 1

Let x be the weight the kitten

z = (x- mean)/σ
1.22 = (x-3.1)/0.9
(1.22)(0.9) = x -3.1

and x = 4.198 pounds 

Answer 2

Use z = (x - μ)/σ

Let x = weight of the kitten

1.22 = (x - 3.1)/0.9

Solve for x.

Can you take it from here?