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JAMB Mathematics Past Questions & Answers - Page 326

1,626.

Evaluate $\frac{21}{9}$ to 3 significant figures

2.30

2.31

2.32

2.33

View answer & explanation

Correct answer is D

$\frac{21}{9} = \frac{7}{3}$

= 2.33 (to 3 sig. figs)

1,627.

Simply $\frac{2\frac{2}{3} \times 1\frac{1}{2}}{4\frac{4}{5}}$

$1\frac{1}{4}$

$1\frac{1}{6}$

$\frac{5}{6}$

$\frac{4}{5}$

View answer & explanation

Correct answer is C

$\frac{2\frac{2}{3} \times 1\frac{1}{2}}{4\frac{4}{5}}$

$\frac{8}{3} \times \frac{3}{2} \div \frac{24}{5}$

$\frac{8}{3} \times \frac{3}{2} \times \frac{5}{24}$

$\frac{5}{6}$

1,628.

Convert 112 $_6$ to a number in base three

2211

2121

1212

1122

View answer & explanation

Correct answer is D

First, convert to base 10

112 $_6$ = (1 x 6 $^2$ ) + (1 x 6 $^1$ ) + (2 x 6 $^0$ )

= 36 + 6 + 2

= 44 $_{10}$

$\begin{array}{c|c} 3 & 44 \\ \hline 3 & 14 & r 2 \\ \hline 3 & 4 & r 2 \\ \hline 3 & 1 & r 1 \\ \hline 3 & 0 & r 1 \end{array}$

Ans = 1122 = D

1,629.

A basket contains 9 apples, 8 bananas and 7 oranges. A fruit is picked from the basket, find the probability that it is neither an apple nor an orange.

$\frac{3}{8}$

$\frac{1}{3}$

$\frac{7}{24}$

$\frac{2}{3}$

View answer & explanation

Correct answer is B

n(apples) = 9
n(bananas) = 8
n(oranges) = 7

n( $\varepsilon$ ) = 24

Hence Prob(not apple, nor orange) = Prob(banana) = $\frac{8}{24}$ = $\frac{1}{3}$

1,630.

What is the probability that an integer x $(1 \leq x \leq 25)$ chosen at random is divisible by both 2 and 3?

$\frac{1}{25}$

$\frac{1}{5}$

$\frac{4}{25}$

$\frac{3}{4}$

View answer & explanation

Correct answer is C

$(1 \leq x \leq 25)$ = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25}

Number N of x divisible by both 2 and 3 is 4.

n( $\varepsilon$ ) = 25

= $\frac{N}{n(\varepsilon)}$

= $\frac{4}{25}$