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.

3,891.

Find the range of values of x for which \(\frac{(x+2)}{4}-\frac{2x-3}{3}<4\)

A.

x > -6

B.

x > -3

C.

x < 8

D.

x < 4

Correct answer is A

\(\frac{x + 2}{4} - \frac{2x - 3}{3} < 4\)

\(\frac{3(x + 2) - 4(2x - 3)}{12} < 4\)

\(3x + 6 - 8x + 12 < 48\)

\(18 - 5x < 48 \implies -5x < 48 - 18\)

\(-5x < 30 \implies x > -6\)

3,892.

The time taken to do a piece of work is inversely proportional to the number of men employed. if it takes 45 men to do a piece of work in 5 days, how long will it take 25 men?

A.

15 days

B.

12 days

C.

5 days

D.

9 days

Correct answer is D

The time (t) to do the work is inversely proportional to the number of workers (n).

\(\implies t \propto \frac{1}{n}\)

\(t = \frac{k}{n}\)

\(5 = \frac{k}{45} \implies k = 45 \times 5 = 225\)

\(\therefore t = \frac{225}{n}\)

For 25 men, \(t = \frac{225}{25} = 9\)

\(\therefore\) 25 men will do the work in 9 days.

3,893.

Solve for x in the equation x\(^3\) - 5x\(^2\) - x + 5 = 0

A.

1, - 1, or 5

B.

1, 1, or -5

C.

-1, 1, or -5

D.

1, 1, or 5

Correct answer is A

x\(^3\) - 5x\(^2\) - x + 5 = 0.

\(x^{2}(x - 5) - 1(x - 5) = 0\)

\((x^2 - 1)(x - 5) = 0 \implies (x - 1)(x + 1)(x - 5) = 0\)

\(\therefore x = 1, -1, 5\)

3,894.

If \(y = x^2 - \frac{1}{x}\). find dy/dx

A.

2x - (1/x2)

B.

2x + x2

C.

2x - x2

D.

2x + (1/x2)

Correct answer is D

\(y = x^{2} - \frac{1}{x} = x^{2} - x^{-1}\)

\(\frac{\mathrm d y}{\mathrm d x} = 2x - (- x^{-2})\)

= \(2x + \frac{1}{x^{2}}\)

3,895.

A circle with radius 5cm has its radius increasing at the rate of 0.2m/s. What will be the corresponding increase in the area?

A.

B.

C.

π

D.

Correct answer is A

Area of the circle (A) = \(\pi r^{2}\)

\(\frac{\mathrm d A}{\mathrm d r} = 2\pi r\)

\(\frac{\mathrm d A}{\mathrm d t} = \frac{\mathrm d A}{\mathrm d r} . \frac{\mathrm d r}{\mathrm d t}\)

\(\frac{\mathrm d A}{\mathrm d t} = 2\pi \times 5 \times 0.2 = 2\pi\)