JAMB Mathematics Past Questions & Answers - Page 332

1,656.

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

A.

2\(\frac{1}{2}\) years

B.

3 years

C.

3\(\frac{1}{2}\) years

D.

1\(\frac{1}{2}\) years

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

A.

0.6

B.

6.2

C.

6.3

D.

0.5

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

A.

36

B.

24

C.

16

D.

38

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

A.

10013

B.

10103

C.

11003

D.

10003

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?

A.

\(\frac{2}{15}\)

B.

\(\frac{1}{10}\)

C.

\(\frac{1}{3}\)

D.

\(\frac{2}{5}\)

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) = \(\frac{1}{3}\)