If a : b = 2 : 7 and 343 is the third proportional to a and b, then the value of b – a is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 70.
Let's assume a : b = 2x : 7x
Now, according to the question,
⇒ 2x : 7x : 343
⇒ 2x/7x = 7x/343
⇒ x = 14
Value of a = 2x = 28
Value of b = 7x = 98
⇒ b - a = 98 - 28 = 70