If at the same rate of interest, in 2 years, the simple interest is ₹42 and the compound interest is ₹43, then what is the principal (in ₹)?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1, i.e., 441.
Let principal = P, rate = R%
SI = (P × R × 2) ÷ 100 = 42
P × R = 2100
R = 2100/P
CI − SI for 2 years = (P × R2) ÷ 10000
⇒ 43 - 42 = (P × R2) ÷ 10000
⇒ P × R2 = 10000
⇒ P × (2100 ÷ P)2 = 10000
⇒ 4410000 ÷ P = 10000
⇒ P = 441