WAEC Mathematics Past Questions & Answers - Page 159

791.

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?

A.

N80,000

B.

N40,000

C.

N2,000

D.

10,000

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

792.

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

A.

1

B.

\(\frac{1}{3}\)

C.

\(\frac{1}{9}\)

D.

\(\frac{1}{27}\)

Correct answer is C

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

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

= \(\frac{1}{3^2}\)

= \(\frac{1}{9}\)

793.

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

A.

least value of x is -3.2

B.

least value of x is -3

C.

greatest value of x is 4.9

D.

greatest value of x is 5

Correct answer is B

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

least value of x is -3

794.

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

A.

29\(\sqrt{5}\)

B.

14\(\sqrt{15}\)

C.

12\(\sqrt{15}\)

D.

11\(\sqrt{15}\)

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\(\sqrt{5}\)

795.

If p \(\alpha \frac{I}{Q}\) which of the following is true?

A.

q \(\alpha p^2\)

B.

q \(\alpha \frac{1}{p^2}\)

C.

q \(\alpha \sqrt{p}\)

D.

q \(\alpha \frac{1}{p}\)

Correct answer is D

p \(\alpha \frac{I}{Q}\); p \(\frac{k}{q}\) (where k is constant)

q = \(\frac{k}{p}\)

q \(\alpha \frac{1}{p}\)