arun borrowed a sum of money from jayant at the rate of 8 % per annum simple interest for the first 4 years , 10 % per annum for the next 6 years and 12 % per annum for the period beyond 10 years . if he pays a total of 12160 as interest only at the end of 15 years , how much money did he borrow ? Choose one:
A) 8000 B) 10000 C) 12000 D) 9000 E) none of these

Rationale: let the principal = p then p × 8 × 4 / 100 + p × 10 × 6 / 100 + p × 12 × 5 / 100 = 12160 ⇒ 152 p = 12160 × 100 or 12160 × 100 / 152 = 8000 answer a
Answer: A