Find the principal which yields a simple interest of Rs. 20 and compound interest of Rs. 22 in two years, at the same percent rate per annum?
Pick.
A) s. 520
B) s. 480
C) s. 420
D) s. 100
E) s. 200
Explanation:   SI in 2 years = Rs. 20, SI in 1 year = Rs. 10   CI in 2 years = Rs. 22   % rate per annum = [(CI – SI) / (SI in 1 year)] *100   = [(22 – 20) / 20] * 100   = 10 % p.a.   Let the principal be Rs. X   Time = T = 2 years   % rate = 10% p.a.   SI = (PRT/100)   20 = (X*10*2) / 100   X = Rs. 100   ANSWER: s. 100
<result>D</result>
Find the principal which yields a simple interest of Rs. 20 and compound interest of Rs. 22 in two years, at the same percent rate per annum?