Exercise 37 Page 557

We are given the scale factor of the computer image to the projected image and the dimensions of the photos on the computer screen. To evaluate the dimensions of the same photos projected on the digital projector, we can use the fact that the ratio of corresponding dimensions is equal to the scale factor. The scale factor=Dimension on a computer/Dimension on a projectorLet's start with the first dimension of the projected image. We can name it x. To do this, we will substitute 14 for the scale factor and 13 for the numerator, as it is the first dimension of the computer image, and solve for x.

1/4=13/x

CrossMult

Cross multiply

1* x=4*13

Multiply

Multiply

x=52

Now, let's do the same with the second dimension of the projected image. Let this be y. The scale factor stays the same, but this time we will substitute 9 14 for the numerator.

1/4=9 14/y

WriteDec

Write as a decimal

1/4=9.25/y

CrossMult

Cross multiply

1* y=4*9.25

Multiply

Multiply

y=37

The photos are 52 inches by 37 inches on the digital projector.