1.  A sum of money amounts to ₹ 9800 after 5 years and ₹ 12005 after 8 years at the same rate of simple interest. The rate of interest per annum is:
A. 5%
B. 8%
C. 12%
D. 15%

Answer: Option C

Explanation:

S.I. for 3 years = ₹ (12005 - 9800) = ₹ 2205.

S.I. for 5 years = ₹ 2205 x 5 = ₹ 3675
3

Principal = ₹ (9800 - 3675) = ₹ 6125.

Hence, rate = 100 x 3675 % = 12%
6125 x 5