1.  If the annual rate of simple interest increases from 10% to 12 %, a man's yearly income increases by ₹ 1250. His principal (in ₹) is :
A. 45,000
B. 50,000
C. 60,000
D. 65,000

Answer: Option B

Explanation:

Let the sum be ₹ X. Then,

X x 25 x 1 - X x 10 x 1 = 1250
2 100 100

<=> 25X - 20X = 250000
<=> 5X = 250000
<=> X = 50000