A person deposited ` 400 for 2 years, ` 550 for 4 years and ` 1200 for 6 years. He received the total simple interest of ` 1020. The rate of interest per annum is
(a)5%
(b)10%
(c)15%
(d)20%
Answer
Answer (as printed): B
Explanation
Let the rate of interest be R% p.a. 400 × R × 2 550 × R × 4 1200 × R × 6 Then, + + = 1020 100 100 100 ⇒ 800R + 220R + 7200R = 102000 ⇒ 10200R = 102000 ⇒ R = 10.
Explanation as extracted from the printed page; notation may be imperfect.