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JAMB Mathematics Past Questions & Answers - Page 231

1,151.

If n is the median and m is the mode of the following set of numbers, 2.4, 2.1, 1.6, 2.6, 2.6, 3.7, 2.1, 2.6, then (n, m) is

(2.6, 2.6)

(2.5, 2.6)

(2.6, 2.5)

(2.5, 2.1)

View answer & explanation

Correct answer is B

Arrange the numbers in order, 1.6, 2.1, 2.1| 2.4, 2.6| 2.6, 2.6, 3.7

n = median = $\frac{2.4 + 2.6}{2}$

= 2.5

m = mode = 2.6

∴ (n, m) = (2.5, 2.6)

1,152.

In a family of 21 people, the average age is 14years. If the age of the grandfather is not counted, the average age drops to 12 years. What is the age of the grandfather?

35 years

40 years

42 years

54 years

View answer & explanation

Correct answer is C

Total age of the whole family = 21 x 14 = 294

Total age without the grandfather = 21 x 12 = 252

Age of grandfather = 294 - 252

= 42 years

1,153.

In preparing rice cutlets, a cook used 75g of rice, 40g of margarine, 105g of meat and 20g of bread crumbs. Find the angle of the sector which represents meat in pie chart

30^o

60^o

112.5^o

157.5^o

View answer & explanation

Correct answer is D

Rice = 75g, Margarine = 40g, Meat = 105g, Bread = 20g, Total = 240

Angle of sector represented by meat

= $\frac{105}{240}$ x $\frac{360°}{1}$ = 157.5°

1,154.

OXYZW is a pyramid with a square base such that OX = OY= OZ = OW = 5cm and XY = XW = YZ = WZ = 6cm. Find the height OT

2 $\sqrt{5}$

4 $\sqrt{3}$

View answer & explanation

Correct answer is D

xz² = 6² + 6²

36 + 36 = 72

xz = $\sqrt{72}$

6 $\sqrt{2}$ = xT

$\frac{6\sqrt{2}}{2}$ = $\frac{3}{\sqrt{2}}$

OT² = 5² + (3 $\sqrt{2}$ )2 = 25 + 18

OT = 4 $\sqrt{3}$

1,155.

A cylindrical metal pipe 1m long has an outer diameter of 7.2cm and an inner diameter of 2.8cm. Find the volume of metal used for the cylinder

440 $\pi$ cm³

1100 $\pi$ cm³

4400 $\pi$ cm³

1100 $\pi$ cm³

View answer & explanation

Correct answer is A

Volume of cylinder pip (V) = $\pi$ h(R $^2$ - r $^2$ )

= 100 $\pi$ (7.2 $^2$ - 2.8 $^2$ )

= 100 $\pi$ (51.84 - 7.84)

= 100 $\pi$ x 44

= 440 $\pi$ cm $^3$