Find the mean proportional between 7921 & 9409?	Select the correct option:
A) 8163
B) 8633
C) 8663
D) 8636
E) none of these

Rationale: "explanation : formula = √ a × b a = 7921 and b = 9409 √ 7921 × 9409 = 89 × 97 = 8633 answer : option b"
Answer: B