Lets use the t-test since the variance of the population is now known. We need to test the hypothesis that H_0: \mu \leq 79 \text{ vs } H_1: \mu > 79 . This is performed in R as follows:
The dimensions of the original photo were 11 inches by 11 inches.
We are informed that the area of the reduced photo is 64 square inches and that In the equation (x – 3)^2 = 64, x represents the side measure of the original photo.
In order to solve for x, we shall first take square roots on both sides of the equation;
The square root of (x – 3)^2 is simply (x - 3).
The square root of 64 is ±8 but we ignore -8 since the dimensions of any figure must be positive.