WAEC Mathematics Past Questions & Answers - Page 154

766.

For what range of values of x is 4x - 3(2x - 1) > 1?

A.

x > -1

B.

x > 1

C.

x < 1

D.

x < -1

Correct answer is C

4x - 3(2x - 1) > 1

4x - 6x + 3 > 1

-2x > 1 - 3; 2x > -2

x < \(\frac{-2}{-2}\)

= x < 1

767.

make w the subject of the relation \(\frac{a + bc}{wd + f}\) = g

A.

\(\frac{a + bc - fg}{dg}\)

B.

\(\frac{a - bc + fg}{dg}\)

C.

\(\frac{a + bc - f}{dg}\)

D.

\(\frac{a + bc - dg}{dg}\)

Correct answer is A

\(\frac{a + bc}{wd + f}\) = g(cross multiply)

a = bc + wdg + fg

wdg = a + bc - fg

w = \(\frac{a + bc - fg}{dg}\)

768.

Which of the following is a factor of 2 - x - x2?

A.

1 - x

B.

1 + x

C.

x - 1

D.

2 - x

Correct answer is A

2 - x - x2; (2 - 2x) + (x - x2)

= 2(1 - x) + x(1 - x)

= (1 - x)(2 + x)

= 1 - x

769.

PQR is an equilateral triangle with sides 2\(\sqrt{3cm}\). calculate its height

A.

1.7cm

B.

3.0cm

C.

3.2cm

D.

3.9cm

Correct answer is B

By Pythagoras theorem

h2 = (2\(\sqrt{3})^2 - (\sqrt{3})^2\)

= 22(\(\sqrt{3})^2 - 3\)

4(3) - 3 = 112 - 3

h2 = 9

h = \(\sqrt{9}\)

= 3cm

770.

At what rate per cent per annum will N520.00 yield a simple interest of N39.00 in three years?

A.

4%

B.

3\(\frac{1}{2}\)%

C.

3%

D.

2\(\frac{1}{2}\)%

Correct answer is D

SI = \(\frac{PRT}{100}\)

39 = \(\frac{520 \times R \times 3}{100}\)

1560R = 3900

R = \(\frac{3900}{1560}\)

= 2.5%

R = 2\(\frac{1}{2}\)%