If a + b = 25 and a – b = 7, then determine the mean proportion of a and b.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 12.
Concept used:
Mean proportion of a and b = √(ab)
Calculations:
a + b = 25 ....(1)
a - b = 7 ....(2)
Adding eq. (1) and (2),
⇒ (a + b) + (a - b) = 25 + 7
⇒ 2a = 32
⇒ a = 16
Substituting the value of 'a' in equation (1),
⇒ 16 + b = 25
⇒ b = 25 - 16 = 9
Hence, the mean proportion = √(16 × 9) = √144 = 12