JAMB Mathematics Past Questions & Answers - Page 124

616.

Find the curved surface area of the frustrum in the figure

A.

16\(\pi \sqrt{10}\)cm2

B.

20\(\pi \sqrt{10}\)cm2

C.

24\(\pi \sqrt{10}\)cm2

D.

36\(\pi \sqrt{10}\)cm2

Correct answer is B

\(\frac{x}{4} = \frac{6 + x}{6}\)

6x = 4(6 + x) = 24 + 4x

x = 12cm 

 CSA = \(\pi RL - \pi rl\)

= \(\pi (6) \sqrt{{18^2} + 6^2} - \pi \times 4 \times \sqrt{{12^2} + 4^2}\)

= 6\(\pi \sqrt{360} - 4 \pi \sqrt{160}\)

= 36\(\pi \sqrt{10} - 16 \pi \sqrt{10}\)

= 20\(\pi \sqrt{10}\)cm2

617.

In the figure, PQR is a semicircle. Calculate the area of the shaded region

A.

125\(\frac{2}{7}\)2

B.

149\(\frac{2}{7}\)cm2

C.

234\(\frac{1}{7}\)cm2

D.

267\(\frac{1}{2}\)cm2

Correct answer is A

No explanation has been provided for this answer.

618.

In the figure, YXZ = 30o, XYZ = 105o and XY = 8cm. Calculate YZ

A.

16\(\sqrt{2}\)cm

B.

8\(\sqrt{2}\)cm

C.

4\(\sqrt{2}\)cm

D.

22cm

Correct answer is C

yzx + 105o + 30o = 180o

yzx = 180 - 155 = 45o

\(\frac{yz}{sin 30^o} = \frac{8}{sin 45^o}\)

yz = \(\frac{8 \sin 30}{sin 45}\)

= 8(\(\frac{1}{2}) = \frac{8}{1} \times \frac{1}{2} \times \frac{\sqrt{2}}{1}\)

= 4 \(\div\) \(\frac{1}{\sqrt{2}}\)

= 4\(\sqrt{2}\)cm

619.

In triangles XYZ and XQP, XP = 4cm, XQ = 5cm and PQ = QY = 3cm. Find ZY

A.

8cm

B.

6cm

C.

4cm

D.

3cm

Correct answer is B

No explanation has been provided for this answer.

620.

In the figure, PS = QS = RS and QSR - 100o, find QPR

A.

40o

B.

50o

C.

80o

D.

100o

Correct answer is B

Since PS = QS = RS

S is the centre of circle passing through P, Q, R /PS/ = /RS/ = radius

QPR \(\pm\) \(\frac{100^o}{2}\) = 50o