Past papers › JAMB 1986 · UME › Question 9 Question JAMB General Maths 1986 Objective Commercial arithmetic Commercial arithmetic
Udoh deposited ₦150.00 in the bank. At the end of 5 years the simple interest on the principal was ₦55.00. At what rate per annum was the interest paid?
A 11 % 11\% 11% B 7 1 3 % 7\frac13\% 7 3 1 % C 5 % 5\% 5% D 3 1 2 % 3\frac12\% 3 2 1 %
Worked solution (try it first) Use
I = P R T 100 I = \dfrac{PRT}{100} I = 100 P R T and make
R R R the subject:
R = 100 I P T R = \dfrac{100I}{PT} R = P T 100 I .
Put in
I = 55 I = 55 I = 55 ,
P = 150 P = 150 P = 150 and
T = 5 T = 5 T = 5 :
R = 5500 750 = 22 3 R = \dfrac{5500}{750} = \dfrac{22}{3} R = 750 5500 = 3 22 .
So the rate is
7 1 3 % 7\frac13\% 7 3 1 % per annum, option B.
Watch out
Divide by the principal as well as the time. 55 ÷ 5 = 11 55 \div 5 = 11 55 ÷ 5 = 11 11 % 11\% 11% Report a problem with this question