Question

A photograph is enlarged to make a poster. The photograph is 10 cm wide and 16 cm high. The poster is 25 cm wide. How high is the poster? Explain your reasoning

Answer 1

40cm

Explanation:

set up a proportion of width to height.

10/16 = 25/x

cross multiply to get 10x = 400

solve for x and get 40 cm

check your answer by seeing that the poster width (25) is 2.5 x larger than the photograph width (10). the height should have the same ratio, so 16 x 2.5, does indeed = 40.