CIE iGCSE Maths E1.12 Rates Exam Style Practice Questions- Paper 2
Question
Kai invests \(\$5000\) in an account paying simple interest at a rate of $r\%$ per year.
At the end of 8 years, the value of his investment is \(\$5700\).
Find the value of r.
▶️Answer/Explanation
$1.75$
Simple Interest Formula:
$
A = P(1 + rt)
$
\( A \) is the final amount (after interest) $= \$5700$
\( P \) is the principal amount (initial investment) $= \$5000$
\( r \) is the interest rate
\( t \) is the time in years $= 8$ years
$
5700 = 5000(1 + r(8))
$
$
\frac{5700}{5000} = 1 + 8r
$
$
1.14 = 1 + 8r
$
$
1.14 – 1 = 8r
$
$
0.14 = 8r
$
$
r = 0.0175
$
$
r = 1.75\%
$
Question
From a sample of 80 batteries, 3 are faulty.
Work out the percentage of faulty batteries.
………………………………………. %
Answer/Explanation
Ans:
3.75 or 3 3/4
Question
Calculate 17.5% of 44kg.
Answer/Explanation
Ans:
7.7 kg
Question
Work out 72 cents as a percentage of 83 cents.
Answer/Explanation
Ans:
86.7 or 86.74 to 86.75 %