JAMB Mathematics Past Questions & Answers - Page 279

1,391.

Calculate the perimeter, in cm, of a sector of a circle of radius 8cm and angle 45^o

2\(\pi\)

8 + 2\(\pi\)

16 + 2\(\pi\)

16 + 16\(\pi\)

Correct answer is C

Perimeter = OP + OQ + PQ

= 8 + 8 + PQ

length PQ = \(\frac{\theta}{360 \times 2\pi r}\)

= \(\frac{45}{360}\) x 2 x \(\pi\) x 8

= 2\(\pi\)

Perimeter of sector 2r + L

Where l = length of arc and r = radius

∴ P = 2(8) + 2\(\pi\)

= 16 + 2\(\pi\)

1,392.

An open rectangular box is made of wood 2cm thick. If the internal dimensions of the box are 50cm long, 36cm wide and 20cm deep, the box volume of wood in the box is

11 520cm³

36 000cm³

38 200cm³

47 520cm³

View answer & explanation

Correct answer is A

Internal dimension are 50cm, 36cm and 20cm

internal volume = 50 x 36 x 20cm³

1000 x 36cm³

= 36000cm³

External dimension are 54cm x 40cm x 22cm

= 2160cm² x 22cm = 47520cm³

Volume of wood = Ext. volume - Int. volume

= 47,520cm³ - 36,000cm³

= 11,520cm³

1,393.

If three angles of a quadrilateral are (3y - x - z)^o, 3x^o, (2z - 2y - x)^o find the fourth angle in terms of x, y and z

(360 - x- y - z)^o

(360 + x + y - z)^o

(180 - x + y + z)^o

View answer & explanation

Correct answer is A

The sum of angles of a quadrilateral is 360^o

∴ (3y - x - z)^o + 3x^o + (2z - 2y - x)^o + p^o = 360^o

Where P is the fourth angle

3y - x - z + 3x + 2z - 2y - x + p = 360^o

p = 360 - (x + y + z)

∴ p = (360 - x - y - z)^o