Question

Calculate the scale factor. A. k=1/7 B. k=5/7 C. k=7/5 D. k=5

Answer 1

Answer is Option B = 5/7

Explanation:

A scale factor is a number which scales, or multiplies, some quantity. In the equation y = Kx, K is the scale factor for x. K is also the coefficient of x, and may be called the constant of proportionality of y to x.  

For big pictures or maps, images should be drawn without affecting the shape in a small paper.  Hence dimension of x is reduced to y with constant proporiton k which is scale factor

Here we find that original length of PC = 21

In image P'C = 15

Hence scale factor=15/21 = 5/7