If a certain sum of money becomes 5 times of its principal in 10 years at simple interest, then the rate of interest is-

Question: If a certain sum of money becomes 5 times of its principal in 10 years at simple interest, then the rate of interest is-

Solution:
ধরি, আসল = P
এবং 10 বছর পরে মোট টাকা = 5P

∴ সরল মুনাফা = মোট টাকা - আসল
= 5P - P
= 4P

আমরা জানি,
সরল মুনাফা = (P × r × n)/100
4P = (P × r × 10)/100
⇒ 4 = r/10
∴ r = 40%

∴ সঠিক উত্তর: গ) 40%