# Simple Interest - Quantitative Aptitude (MCQ) questions for Q. 21568

**Q. Find the principal which yields a simple interest of Rs. 20 and compound interest of Rs. 21 in two years, at the same percent rate per annum?***- Published on 06 May 16***a.** Rs. 520

**b.** Rs. 480

**c.** Rs. 420

**d.** Rs. 200

**ANSWER: Rs. 200**

SI in 2 years = Rs. 20, SI in 1 year = Rs. 10

CI in 2 years = Rs. 21

**% rate per annum = [(CI – SI) / (SI in 1 year)] *100**

= [(21 – 20) / 20] * 100

= 5 % p.a.

Let the principal be Rs. X

Time = T = 2 years

% rate = 5% p.a.

SI = (PRT/100)

20 = (X*5*2) / 100

X = Rs. 200