Question

If 343 is the third proportional of a and b , where a:b =1:7 , then find value of a+b

Answer 1

Answer:  56

Step-by-step explanation:

Given - The third proportional of A and B is 343

          - A : B = 1 : 7

= A : B :: B : 343

So now we find the product of the means and extremes. We then get :-

B² = 343A.......................(1)

Also given,  A : B = 1 : 7

A : B = 1 : 7

A/B = 1/7

B = 7A

Putting the value of B = 7A in equation (1), we get

(7A)² = 343A

49A² = 343A

A = 343/7

A = 7

So B = 7 × 7 = 49

Therefore A + B = 7 + 49 = 56

Hope it helps!