Question

If the compound ratio of 7:5and8:x is 84:60.Find x.

Answer 1

Compound ratio of 7:5 and8:x =84:60
7×5 :8×x=84:60
56:5x=84:60
Product of extremes = product of means
56×60=5x×84
56×60/84=5x
40=5x
40/5=x
x=8

Answer 2

Answer:  The required value of x is 8.

Step-by-step explanation:  Given that the compound ratio of the ratios 7 : 5 and 8 : x is 84 : 60.

We are to find the value of x.

We know that

the compound ratio for the ratios a : b and c : d is ac : bd.

So, according to the given information, we get

$7\times8:5\times x=84:60\\\\\Rightarrow 56:5x=84:60\\\\\Rightarrow \dfrac{56}{5x}=\dfrac{84}{60}\\\\\\\Rightarrow \dfrac{56}{x}=\dfrac{84}{12}\\\\\\\Rightarrow \dfrac{56}{x}=7\\\\\\\Rightarrow x=\dfrac{56}{7}\\\\\Rightarrow x=8.$

Thus, the required value of x is 8.