Mathematics questions and answers

Mathematics Questions and Answers

How good are you with figures and formulas? Find out with these Mathematics past questions and answers. This Test is useful for both job aptitude test candidates and students preparing for JAMB, WAEC, NECO or Post UTME.

3,776.

Find the curved surface area of a cone with circular base diameter 10 cm and height 12 cm

A.

25 πcm2

B.

65 πcm2

C.

120 πcm2

D.

156 πcm2

Correct answer is B

L2 = 122 + 52
= 144 + 25
= 169
L = √169
= 13
Curved surface Area = πrL
= 5/1 * 13/1 * π
= 65πcm2

3,777.

A sector of a circle has an area of 55 cm2. If the radius of the circle is 10 cm, calculate the angle of the sector
[π = 22/7]

A.

45o

B.

63o

C.

75o

D.

90o

Correct answer is B

Area of a sector = \(\frac{\theta}{360}\times \pi r^2\\55=\frac{\theta}{360}\times \frac{22}{7}\times \frac{10\times 10}{1}\\\theta=\frac{360 \times 55 \times 7}{22 \times 10 \times 10}\\\theta = 63^{\circ}\)

3,778.

The sum of the interior angle of a regular polygon is 1800o. Calculate the size of one exterior angle of the polygon

A.

30o

B.

24o

C.

18o

D.

12o

Correct answer is A

Sum of interior ∠s = 1800o
∴(n - 2) 180o = 1800o
180n -360o = 1800o
180n = 1800o + 360o
180n = 2160o
n = 2160o/180o
n = 12 sides
Each exterior ∠ = 360o/n
= 360o/12
= 30o

3,779.

An operation * is defined on the set of real numbers by a * b = ab + 2(a + b + 1). find the identity element

A.

2

B.

1

C.

-1

D.

-2

Correct answer is C

a * b = ab + 2(a + b + 1)
let e be the identity element
∴ a * e = e * a = a
∴ a * e = a
ae + 2(a + e + 1) = a
ae + 2a + 2e + 2 = a
ae + 2e = a - 2a = 2
(a + 2)e = -a - 2
e = -a-2 / (a+2)
e = -(a+2) / (a+2)
e = -1

3,780.

Find the sum of the first 20 terms of the series 8, 12, 16, ....., 96

A.

1400

B.

1040

C.

960

D.

920

Correct answer is D

8, 12, 16, .....96
a = 8, d = 4, l = 96, n = 20
\(S_{20} = \frac{n}{2}(2a + (n-1)d\)

\(S_{20} = \frac{20}{2}((2\times 8) + (20-1)\times 4)\)

\(S_{20} = 10(16 + (19\times 4)) = 10 \times 92\)

=920