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WAEC Mathematics Past Questions & Answers - Page 171

851.

$\frac{1}{3}$

$\frac{1}{9}$

$\frac{1}{27}$

Correct answer is C

$\frac{3x^{3}}{(3x)^{3}}\\ \frac{3x^{3}}{3x\times 3x\times 3x}=\frac{3\times x\times x\times x}{3\times 3\times 3\times x\times x\times x}=\frac{1}{9}$

852.

Which of the following is true for the set $P = \{-3.2\leq x< 5\}$ 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 A

No explanation has been provided for this answer.

853.

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

$29\sqrt{5}$

$14\sqrt{15}$

$12\sqrt{15}$

$11\sqrt{5}$

View answer & explanation

Correct answer is A

$3\sqrt{45}-12\sqrt{5}+16\sqrt{20}\\ 3\sqrt{5\times 9}-12\sqrt{5}+16\sqrt{4\times 5}\\ 3\times 3\sqrt{5}-12\sqrt{5}+16\times 2\sqrt{5}\\ 9\sqrt{5}-12\sqrt{5}+32\sqrt{5}\\ 29\sqrt{5}$

854.

If $p\propto \frac{1}{q}$ , which of the following is true?

$\propto p^{2}$

$p\propto \frac{1}{q^{2}}$

$q\propto \sqrt{p}$

$q\propto \frac{1}{p}$

View answer & explanation

Correct answer is D

$p\propto \frac{1}{q} = q \propto \frac{1}{p}$

855.

Simplify $(0.3\times 10^{5})\div (0.4\times 10^{7})$ leaving your answer in standard form

$7.5\times 10^{-4}$

$7.5\times 10^{-3}$

$7.5\times 10^{-2}$

$7.5\times 10^{-1}$

View answer & explanation

Correct answer is B

$(0.3\times 10^{5})\div (0.4\times 10^{7})\\ \frac{3}{10}\times 10^{5}\div \frac{4}{10}\times 10^{7}=3\times 10^{4}\div 4\times 10^{6}\\ \frac{3\times 10^{4}}{4\times 10^{7}}=\frac{3}{4}\times 10^{-2}=0.75\times 10^{-2}\\ 7.5\times 10^{-3}$