WAEC Mathematics Past Questions & Answers - Page 234

1,166.

Simplify 3.72 x 0.025 and express your answer in the standard form

A.

\(9.3\times 10^3\)

B.

\(9.3\times 10^2\)

C.

\(9.3\times 10^{-2}\)

D.

\(9.3\times 10^{-3}\)

Correct answer is C

\(3.72 \times 0.025 = 0.093 = 9.3\times 10^{-2}\)

1,167.

The height of a pyramid on square base is 15cm. If the volume is 80cm\(^3\), find the length of the side of the base

A.

3.3cm

B.

5.3cm

C.

4.0cm

D.

8.0cm

Correct answer is C

Volume = \(\frac{1}{3} b^2 h\)

\(\therefore b = \sqrt{\frac{3v}{h}}\)

\(b = \sqrt{\frac{3(80)}{15}} \)

\(b = \sqrt{16} = 4.0 cm\)

1,168.

In the diagram, PQST and QRST are parallelograms. Calculate the area of the trapezium PRST.

A.

60cm2

B.

50cm2

C.

40cm2

D.

30cm2

Correct answer is D

PR = 4 + 4 = 8 cm

Area of trapezium = \(\frac{1}{2} (a + b) h\)

= \(\frac{1}{2} (4 + 8) \times 5\)

= 30 cm\(^2\)

1,169.

A pole of length L leans against a vertical wall so that it makes an angle of 60o with the horizontal ground. If the top of the pole is 8m above the ground, calculate L.

A.

\(16\sqrt{3}m\)

B.

\(4\sqrt{3}m\)

C.

\(\frac{\sqrt{3}}{16}\)

D.

\(\frac{16\sqrt{3}}{3}\)

Correct answer is D

\(sin 60 = \frac{8}{L} = 8 \div \frac{\sqrt{3}}{2}; L = \frac{8}{sin 60}=\frac{16}{\sqrt{3}}\)
When we rationalize gives \(\frac{16\sqrt{3}}{3}\)

1,170.

The diagram shows the position of three ships A, B and C at sea. B is due north of C such that |AB| = |BC| and the bearing of B from A = 040°. What is the bearing of A from C

A.

040o

B.

070o

C.

110o

D.

290o

Correct answer is D

< ABC = 40° (alternate angles)

\(\therefore\) < ACB = \(\frac{180° - 40°}{2}\)

= 70°

\(\therefore\) Bearing of A from C = 360° - 70° 

= 290°