WAEC Mathematics Past Questions & Answers - Page 32

156.

The dimension of a rectangular base of a right pyramid is 9 cm by 5cm. If the volume of the pyramid is 105 cm\(^3\), how high is the pyramid? 

A.

10cm

B.

6cm

C.

8cm

D.

7cm

Correct answer is D

Volume = \(\frac{1}{3}\) x 9 x 5 x h

105 = \(\frac{1}{3}\) x 9 x 5 x h

\(\frac{105}{15} = \frac{15h}{15}\)

h = 7cm 

157.

If tan y is positive and sin y is negative, in which quadrant would y lie? 

A.

First and third only

B.

First and second only

C.

Third only

D.

Second only

Correct answer is C

No explanation has been provided for this answer.

158.

Fati buys milk at ₦x per tin sells each at a profit of ₦y. If she sells 10 tins of milk, how much does she receives from the sales?

A.

₦(xy + 10)

B.

₦(x + 10y)

C.

₦(10x + y)

D.

₦10(x + y)

Correct answer is D

Selling Price for each = ₦x + ₦y 

= 10(₦x + ₦y)

159.

A fence 2.4 m tall, is 10m away from a tree of height 16m. Calculate the angle of elevation of the top of the tree from the top of the fence. 

A.

76.11\(^o\)

B.

53.67\(^o\)

C.

52.40\(^o\)

D.

51.32\(^o\)

Correct answer is B

Tan \(\theta\) = \(\frac{13.6}{10}\)

= tan\(^{-1}\)(1.36)

\(\theta\) = 53.67\(^o\)

160.

In the diagram, XYZ is an equilateral triangle of side 6cm and Y is the midpoint of \(\overline{XY}\). Find tan (< XZT) 

A.

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

B.

\(\frac{\sqrt{3}}{2}\)

C.

\(\sqrt{3}\)

D.

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

Correct answer is A

ZT = \(\sqrt{6^2 - 3^2}\)

ZT = \(\sqrt{27}\) = \(3\sqrt{3}\)

tan (< XZT) =  \(\frac{3}{3\sqrt{3}}\)

= - \(\frac{1}{\sqrt{3}}\)