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.

2,126.

If two dice are thrown together, what is the probability of obtaining at least a score of 10?

A.

\(\frac{1}{6}\)

B.

\(\frac{1}{12}\)

C.

\(\frac{5}{6}\)

D.

\(\frac{11}{12}\)

Correct answer is A

The total sample space when two dice are thrown together is 6 x 6 = 36

\(\begin{array}{c|c} & 1 & 2 & 3 & 4 & 5 & 6\\ 1. & 1.1 & 1.2 & 1.3 & 1.4 & 1.5 & 1.6\\ 2 & 2.1 & 2.2 & 2.3 & 2.4 & 2.5 & 2.6\\3 & 3.1 & 3.2 & 3.3 & 3.4 & 3.5 & 3.6\\ 4 & 4.1 & 4.2 & 4.3 & 4.4 & 4.5 & 4.6\\ 5 & 5.1 & 5.2 & 5.3 & 5.4 & 5.5 & 5.6\\6 & 6.1 & 6.2 & 6.3 & 6.4 & 6.5 & 6.6 \end{array}\)

At least 10 means 10 and above

P(at least 10) = \(\frac{6}{36}\)

= \(\frac{1}{6}\)

2,127.

If x and y represent the mean and the median respectively of the following set of numbers 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, find the \(\frac{x}{y}\) correct to one decimal place

A.

18

B.

15

C.

1.0

D.

5

Correct answer is C

Mean \(\bar{x}\) = \(\frac{156}{10}\) = 15.6

Median = \(\bar{y}\) = \(\frac{15 + 16}{2}\)

\(\frac{31}{2}\) = 15.5

\(\frac{x}{y}\) = \(\frac{15.6}{15.5}\) = 1.0065

1.0(1 d.p)

2,128.

PQR is a triangle in which PQ = 10cm and QPR = 60oS is a point equidistant from P and Q. Also S is a point equidistant from PQ and PR. If U is the foot of the perpendicular from S on PR, find the length SU in cm to one decimal place

A.

2.7

B.

4.33

C.

3.1

D.

3.3

Correct answer is B

\(\bigtriangleup\)PUS is right angled

\(\frac{US}{5}\) = sin60o

US = 5 x \(\frac{\sqrt{3}}{2}\)

= 2.5\(\sqrt{3}\)

= 4.33cm

2,129.

If a metal pipe 10cm long has an external diameter of 12cm and a thickness of 1cm find the volume of the metal used in making the pipe

A.

120\(\pi\)cm3

B.

110\(\pi\)cm3

C.

60\(\pi\)cm3

D.

50\(\pi\)cm3

Correct answer is B

The volume of the pipe is equal to the area of the cross section and length.

let outer and inner radii be R and r respectively.

Area of the cross section = (R2 - r2)

where R = 6 and r = 6 - 1

= 5cm

Area of the cross section = (62 - 52)\(\pi\) = (36 - 25)\(\pi\)cm sq

vol. of the pipe = \(\pi\) (R2 - r2)L where length (L) = 10

volume = 11\(\pi\) x 10

= 110\(\pi\)cm3

2,130.

If \(\cos^2 \theta + \frac{1}{8} = \sin^2 \theta\), find \(\tan \theta\).

A.

3

B.

\(\frac{3\sqrt{7}}{7}\)

C.

3\(\sqrt{7}\)

D.

\(\sqrt{7}\)

Correct answer is B

\(\cos^2 \theta + \frac{1}{8} = \sin^2 \theta\)..........(i)

from trigometric ratios for an acute angle, where \(cos^{2} \theta + \sin^2 \theta = 1\) ........(ii)

Substitute for equation (i) in (i) = \(\cos^2 \theta + \frac{1}{8} = 1 - \cos^2 \theta \)

= \(\cos^2 \theta + \cos^2 \theta = 1 - \frac{1}{8}\)

\(2\cos^2 \theta = \frac{7}{8}\)

\(\cos^2 \theta = \frac{7}{2 \times 8}\)

\(\frac{7}{16} = \cos \theta\)

\(\sqrt{\frac{7}{16}}\) = \(\frac{\sqrt{7}}{4}\)

but cos \(\theta\) = \(\frac{\text{adj}}{\text{hyp}}\)

\(opp^2 = hyp^2 - adj^2\)

\(opp^2 = 4^2  - (\sqrt{7})^{2}\)

= 16 - 7

opp = \(\sqrt{9}\) = 3

\(\tan \theta = \frac{\text{opp}}{\text{adj}}\)

= \(\frac{3}{\sqrt{7}}\)

\(\frac{3}{\sqrt{7}}\) x \(\frac{\sqrt{7}}{\sqrt{7}}\) = \(\frac{3\sqrt{7}}{7}\)