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JAMB Mathematics Past Questions & Answers - Page 254

1,266.

express 62 $\div$ 3 as a decimal correct to 3 significant figures

20.6

20.667

20.67

20.7

View answer & explanation

Correct answer is D

$\frac{62}{3}$ = 20.6666.....

= 20.7 to 3 sig. fig.

1,267.

Find correct to 3 decimal places ( $\frac{1}{0.05}$ + $\frac{1}{5.005}$ ) - (0.05 x 2.05)

99.998

98.999

89.899

9.998

View answer & explanation

Correct answer is A

( $\frac{1}{0.05}$ + $\frac{1}{5.005}$ ) - (0.05 x 2.05)

( $\frac{1}{0.05}$ x 5.005) - (0.05 x 2.05)

$\frac{5.005}{0.05}$ - 0.1025

100.1 - 0.1025

= 99.9975

99.998 to 3 decimal place.

1,268.

If 2257 is the result of subtracting 4577 from 7056 in base n, find n

View answer & explanation

Correct answer is A

$\begin{array}{c|c} 7056 \\ \text{- 4577} \\\hline 2257 \end{array}$
By trial and error method

Let the base to 8

i.e. Let n = 8 and it is easily verified that the subtraction holds.

The subtraction does not hold when other values of n are tried

n = 8

1,269.

Simplify 3 $\frac{1}{3}$ - 1 $\frac{1}{4}$ x $\frac{2}{3}$ + 1 $\frac{2}{5}$

View answer & explanation

Correct answer is C

3 - $\frac{1}{3}$ - ( $\frac{5}{4}$ x $\frac{2}{3}$ ) + 1 $\frac{2}{5}$

= $\frac{10}{3}$ - $\frac{5}{6}$ + $\frac{7}{5}$

= $\frac{100 - 25 + 42}{30}$

= $\frac{117}{30}$

= 3.9

$\approx$ 4