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.

111.

If D = \(\begin{bmatrix}2& -1&3\\4&1&2\\1&-3&1\\\end{bmatrix}\)

Find |D|

A.

16

B.

14

C.

-23

D.

-37

Correct answer is C

\(\begin{bmatrix}2& -1&3\\4&1&2\\1&-3&1\\\end{bmatrix}\)

= 2[(1 x 1) - (2 x -3)] - (-1)[(4 x 1) - (2 x 1)] + 3[(4 x -3) - (1 x 1)]

= 2(1 - (-6)) + 1(4 - 2) + 3(-12 - 1)

= 2(1 + 6) + 1(2) + 3(-13)

= 2(7) + 1(2) + 3(-13)

= 14 + 2 - 39

∴ |D| = -23

112.

A committee of 5 people is to be chosen from a group of 6 men and 4 women. How many committees are possible if there is to be a majority of women?

A.

60

B.

15

C.

66

D.

4

Correct answer is C

If the majority are women implies that:

3 Women and 2 Men Or 4 Women and 1 Man

= \(^4C_3 \times^6C_2+^4C_4\times^6C_1\)

= \(4 \times 15 + 1 \times 6\)

= 60 + 6 = 66
 

113.

The ages of students in a small primary school were recorded in the table below.

 Age                   5 - 6              7 - 8        9 -10
Frequency           29               40          38 


Estimate the mean

A.

7.7

B.

7.5

C.

7.8

D.

7.6

Correct answer is A

Class Interval          Class Mark          Frequency (f)               fx       
        5 - 6              5.5                29 5.5 x 29 = 159.5
        7 - 8              7.5                40 7.5 x 40 = 300
       9 - 10              9.5                38 9.5 x 38 = 361
    \(\sum f = 107\) \(\sum fx = 820.5\)


Mean = \(\frac{\sum fx}{\sum f} = \frac {820.5}{107}\) = 7.7 (1 d.p)

 

114.

Evaluate the following limit: \(lim_{x\to2} \frac {x^2 + 4x - 12}{x^2 - 2x}\)

A.

4

B.

8

C.

0

D.

2

Correct answer is A

\(lim_{x\to2} \frac {x^2 + 4x - 12}{x^2 - 2x}\) = \(lim_{x\to2} \frac {(x - 2)(x + 6)}{x(x - 2)}\)

\(lim_{x\to2} \frac {x + 6}{x}\)

\(\frac {2 + 6}{2} = \frac {8}{2}\) = 4

115.

At simple interest, a man made a deposit of some money in the bank. The amount in his bank account after 10 years is three times the money deposited. If the interest rate stays the same, after how many years will the amount be five times the money deposited?

A.

15 years

B.

25 years

C.

20 years

D.

30 years

Correct answer is C

Amount (A) = Principal (P) + Interest (I) i.e. A = P + I

1 = \(\frac {PTR}{100}\)

A = 3P; T = 10 years (Given)

Since A = P + I

\(\implies 3P = P + \frac {P\times 10 \times R}{100}\)

\(\implies 3P = P + \frac {10PR}{100}\)

\(\implies 3P = P + \frac {PR}{10}\)

\(\implies 3P - P = \frac {PR}{10}\)

\(\implies 2P = \frac {PR}{10}\)

\(\implies \frac {2P}{1} = \frac {PR}{10}\)

\(\implies\) PR = 20P

\(\therefore\) R = 20%

Since the rate stays the same

A = 5P; R = 20%;T =?; A  =P + I

\(\implies 5P = P + \frac {p \times T \times 20}{100}\)

\(\implies 5P - P = \frac {2PT}{10}\)

\(\implies 4P = \frac {2PT}{10}\)

\(\implies 2P = \frac {PT}{10}\)

\(\implies\) PT = 20P

\(\therefore\) T = 20 years