Question

compound ratio of 3:8 and 7:5 is 63:x. then find the value of "x"

Answer 1

compound ratio is the product of two ratios

therefore 3:8 multiplied by 7:5 is 21: 40

63 divide by 21 is 3 so you multiply 40 by 3 to get:

63:120

x=120

Answer 2

we know, if two ratios a : b and c : d are given then, compound ratio of given two ratios is given by ac : bd .

now come to the question,
we have given compound ratio 63 : x of 3 : 8 and 7 : 5 .

so, 63 : x = 3 × 7 : 8 × 5

or, 63 : x = 21 : 40

or, 63 : x = 63 : 120

compare both sides,

x = 120

hence, value of x = 120