JAMB Mathematics Past Questions & Answers - Page 126

626.

On the curve, the points at which the gradient of the curve is equal to zero are

A.

c, d, f. i, l

B.

b, e, g, j, m

C.

a, b, c, d, f, i, j, l

D.

c, d, f, h, i, l

Correct answer is B

The gradient of any curve is equal to zero at the turning points. i.e. maximum or minimum points. The points in the above curve are b, e, g, j, m

627.

In the figure, a solid consists of a hemisphere surmounted by a right circular cone, with radius 3.0cm and height 6.0cm. Find the volume of the solid

A.

36\(\pi\)cm 3

B.

54\(\pi\)cm 2

C.

18\(\pi\)cm 2

D.

108\(\pi\)cm 2

Correct answer is A

The volume of the solid = vol. of cone + vol. of hemisphere

volume of cone = \(\frac{1}{3} \pi r^2 h\)

= \(\frac{1 \pi}{3} \times (3)^2 x 6 = 18 \pi cm^2\)

vol. of hemisphere = \(\frac{4 \pi r^3}{6} = \frac{2 \pi r^3}{3}\)

= \(\frac{2 \pi}{3} \times (3)^3 = 18\pi cm^3\)

vol. of solid = 18\(\pi\) + 18\(\pi\)

= 36\(\pi\)cm3

628.

In the figure, XR and YQ are tangents to the circle YZXP if ZXR = 45° and YZX = 55°, Find ZYQ

A.

135O

B.

125O

C.

100O

D.

90O

Correct answer is A

< RXZ = < ZYX = 45O(Alternate segment)

< ZYQ = 90 + 45

= 135°

629.

In the figure, PS = RS = QS and QRS = 50°. Find QPR

A.

25O

B.

40O

C.

50O

D.

65O

Correct answer is A

In the figure PS = RS = QS, they will have equal base QR = RP

In angle SQR, angle S = 50O

In angle QRP, 65 + 65 = 130O

Since RQP = angle RPQ = \(\frac{180 - 130}{2}\)

= \(\frac{50}{2} = 25^o\)

QPR = 25°

630.

In the figure, STQ = SRP, PT = TQ = 6cm and QS = 5cm. Find SR

A.

\(\frac{47}{5}\)

B.

5

C.

\(\frac{32}{5}\)

D.

\(\frac{22}{5}\)

Correct answer is A

From similar triangle, \(\frac{QS}{QP} = \frac{TQ}{QR} = \frac{5}{12} = \frac{6}{QR}\)

QT = \(\frac{6 \times 12}{5} = \frac{72}{5} = SR = QR - QS\)

= \(\frac{72}{5} - 5 = \frac{72 - 25}{5}\)

= \(\frac{47}{5}\)