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JAMB Mathematics Past Questions & Answers - Page 214

1,066.

Find the reciprocal of $\frac{\frac{2}{3}}{\frac{1}{2} + \frac{1}{3}}$

$\frac{4}{5}$

$\frac{5}{4}$

$\frac{2}{5}$

$\frac{6}{7}$

View answer & explanation

Correct answer is B

$\frac{2}{3}$ = $\frac{2}{3}$

= $\frac{2}{3}$ x $\frac{6}{5}$

= $\frac{4}{5}$

reciprocal of $\frac{4}{5}$ = $\frac{1}{\frac{4}{5}}$

= $\frac{5}{4}$

1,067.

Find the smallest number by which 252 can be multiplied to obtain a perfect square

View answer & explanation

Correct answer is D

$252 = 2^{2} \times 3^{2} \times 7$

$\therefore$ To make 252 a perfect square, the smalest number to multiply with = 7.

$252 \times 7 = 1764 = 42^{2}$

1,068.

Divide the L.C.M of 48, 64, and 80 by their H.C.F

View answer & explanation

Correct answer is D

48 = 2⁴ x 3, 64 = 2⁶, 80 = 2⁴ x 5

L.C.M = 2⁶ x 3 x 5

H.C.F = 2⁴

$\frac{2^6 \times 3 \times 5}{2^4}$

= 2² x 3 x 5

= 4 x 3 x 5

= 12 x 5

= 60

1,069.

If Musa scored 75 in biology instead of 57, his average mark in four subjects would have been 60. What was his total mark?

282

240

222

210

View answer & explanation

Correct answer is C

Let x represent Musa's total mark when he scores 57 in biology and Let Y represent Musa's total mark when he now scored 75 in biology, if he scored 75 in biology his new total mark will be $\frac{Y}{4}$ = 60, y = 4 x 60 = 240

To get his total mark when he scored 57, subtract 57 from 75 to give 18, then subtract this 18 from the new total mark(ie. 240)

= 240 - 18

= 222