A sum of money becomes five times at 8% simple rate of interest per annum. At what rate percent will it become seven fold?
Answer & explanation
Correct answer: option 3
Let principal be P and time be T,
Amount = P(1 + \(\frac{8T}{100}\))
⇒ 5P = P(1 + \(\frac{8T}{100}\))
⇒ 5 = 1 + \(\frac{8T}{100}\)
⇒ \(\frac{8T}{100}\) = 4
⇒ T = 50
Now,
⇒ 7P = P(1 + \(\frac{RX50}{100}\))
⇒ 7 = 1 + \(\frac{50R}{100}\)
⇒ R = 12%