Use cross products to determine which ratio forms a proportion with 9/4

Question

5/3
27/12
36/20
18/4

Answer 1

To determine which ratio forms a proportion with 9/4, we need to find the ratio that has the same cross product as 9/4.

The cross product of a ratio is found by multiplying the numerator of one ratio by the denominator of the other ratio. So, the cross product of 9/4 and 5/3 is:

(9 * 3) / (4 * 5) = 27/20

The cross product of 9/4 and 27/12 is:

(9 * 12) / (4 * 27) = 108/108 = 1

The cross product of 9/4 and 36/20 is:

(9 * 20) / (4 * 36) = 180/144 = 5/4

The cross product of 9/4 and 18/4 is:

(9 * 4) / (4 * 18) = 36/72 = 1/2

Therefore, the ratio that forms a proportion with 9/4 is 36/20.