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JAMB Mathematics Past Questions & Answers - Page 332

1,656.

Calculate the time taken for N3000 to earn N600 if invested at 8% simple interest

2 $\frac{1}{2}$ years

3 years

3 $\frac{1}{2}$ years

1 $\frac{1}{2}$ years

View answer & explanation

Correct answer is A

Using $S.I =\frac{P \times T \times R}{100}$

$600 =\frac{3000 \times T \times 8}{100}$

$T =\frac{600 \times 100}{3000 \times 8}$

$\frac{20}{8}$

= 2 $\frac{1}{2}$ years

1,657.

Evaluate $\frac{1.25 \times 0.025}{0.05}$ , correct to 1 decimal place

0.6

6.2

6.3

0.5

View answer & explanation

Correct answer is A

$\frac{1.25 \times 0.025}{0.05}$

$= \frac{125 \times 10^{-2} \times 25 \times 10^{-3}}{5 \times 10^{-2}}$

= 125 x 5 x 10^-3

= 625 x 0.001

= 0.625

= 0.6 Approx to 1 d.p.

1,658.

3 girls share a number of apples in the ration 5:3:2. If the highest share is 40 apples, find the smallest share

View answer & explanation

Correct answer is C

The sum, S of ratio is S = 5 + 3 + 2 = 10.

But highest share = $\frac{5}{10} \times T$ , where T is the total number of apples.

Thus, $40 = \frac{5}{10} \times T$ ,

given 40 x 10 = 5T,

$T = \frac{40 \times 10}{5} = 80$

Hence the smallest share = $\frac{2}{10} \times 80$

= 16 apples

1,659.

Convert 27₁₀ to another number in base three

1001₃

1010₃

1100₃

1000₃

View answer & explanation

Correct answer is D

$\begin{array}{c|c} 3 & \text{27 rem 0} \\ \hline 3 & \text{ 9 rem 0} \\ \hline 3 & \text{ 3 rem 0} \\ \hline 3 & \text{ 1 rem 1}\\ \hline & 0 \end{array}$

Hence the correct answer is 1000₃

1,660.

A number is chosen at random from 10 to 30 both inclusive. What is the probability that the number is divisible by 3?

$\frac{2}{15}$

$\frac{1}{10}$

$\frac{1}{3}$

$\frac{2}{5}$

View answer & explanation

Correct answer is C

Sample space S = {10, 11, 12, ... 30}

Let E denote the event of choosing a number divisible by 3

Then E = {12, 15, 18, 21, 24, 27, 30} and n(E) = 7

Prob (E) = $\frac{n(E)}{n(S)}$

Prob (E) = $\frac{7}{21}$

Prob (E) = $\frac{1}{3}$