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WAEC Mathematics Past Questions & Answers - Page 158

786.

N140,000 is shared between Abu, Kayode and Uche. Abu has twice as much as Kayode and Kayode has twice as much as Uche. What is Kayode'sshare?

N80,000

N40,000

N2,000

10,000

View answer & explanation

Correct answer is B

Let Abu's share = 2x;

Kayode's = x

Uche's share = $\frac{x}{2}$

Total: 2x + x + $\frac{x}{2}$ = N140,000

$\frac{7x}{2}$ = N140,000

x = $\frac{280,000}{7}$ = N40,000

Kayode's share = N40,000

787.

Simplify $\frac{3x^3}{(3x)^3}$

$\frac{1}{3}$

$\frac{1}{9}$

$\frac{1}{27}$

View answer & explanation

Correct answer is C

$\frac{3x^3}{(3x)^3}$ = $\frac{3 \times x^3}{3^3 \times x^3}$

= $\frac{3 \times x^3}{3 \times 3 \times 3 \times x^3}$

= $\frac{1}{3^2}$

= $\frac{1}{9}$

788.

Which of the following statement is true for the ste P = {-3.2 $\leq$ x < 5} where x is an integer?

least value of x is -3.2

least value of x is -3

greatest value of x is 4.9

greatest value of x is 5

View answer & explanation

Correct answer is B

p = {-3.2.....4.9}; Since x is an integer

least value of x is -3

789.

Simplify 3 $\sqrt{45} - 12\sqrt{5} + 16\sqrt{20}$ , leaving your answer in surd form.

29 $\sqrt{5}$

14 $\sqrt{15}$

12 $\sqrt{15}$

11 $\sqrt{15}$

View answer & explanation

Correct answer is A

3 $\sqrt{45} - 12\sqrt{5} + 16\sqrt{20}$

= 3 x $\sqrt{9 \times 5} - 12 \times \sqrt{5} + 16 \times \sqrt{4 \times 5}$

= 3 x 3 x $\sqrt{5} - 12 \times \sqrt{5} + 16 \times 2 \times \sqrt{5}$

= 9 $\sqrt{5} - 2 \sqrt{5} + 32 \sqrt{5}$

= 9 $\sqrt{5} + 32\sqrt{5} - 12\sqrt{5}$

= 29 $\sqrt{5}$