JAMB Mathematics Past Questions & Answers - Page 184

917.

If \(\frac{3e + f}{3f - e}\) = \(\frac{2}{5}\), find the value of \(\frac{e + 3f}{f - 3e}\)

A.

\(\frac{5}{2}\)

B.

1

C.

\(\frac{26}{7}\)

D.

\(\frac{1}{3}\)

Correct answer is C

\(\frac{3e + f}{3f - e}\) = \(\frac{2}{5}\)

= 3e + f

= 2 x 1

\(\frac{-e + 3f}{3e - f}\) = \(\frac{5 \times 3}{2}\)

= \(\frac{3e + 9f = 15}{10f = 17}\)

f = \(\frac{17}{10}\)

Sub. for equ. (1)

3e + \(\frac{17}{10}\) = 2

3e = 2 - \(\frac{17}{10}\)

\(\frac{3}{10}\)

e = \(\frac{3}{10}\) x \(\frac{1}{3}\)

= \(\frac{1}{10}\)

= e + 3f = \(\frac{1}{10}\) + \(\frac{3 \times}{10}\) = \(\frac{52}{10}\)

f - 3e = \(\frac{17}{10}\) - 3 x \(\frac{1}{10}\)

= \(\frac{14}{10}\)

= \(\frac{52}{10}\) x \(\frac{10}{14}\)

= \(\frac{26}{7}\)

918.

The quantity y is partly constant and partly varies inversely as the square of x. With P and Q as constants, a possible relationship between x and y is

A.

y = Q + \(\frac{P}{x^2}\)

B.

y = Q + px

C.

y = \(\frac{PQ}{x^2}\)

D.

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

Correct answer is A

Given the above statement,

\(y = Q + \frac{P}{x^{2}}\)

919.

Express 130 kilometers per second in meters per hour

A.

7.8 x 10-5

B.

4.68 x 106

C.

7,800,000

D.

4.68 x 108

E.

7.80 x 105

Correct answer is D

1km = 1000m

60sec. = 1 mins

60 mins. = 1 hr

130000m per sec = 130000 x 3600

= 468000000m/hr

= 468 x 108 m/hr

920.

A stone Q is tied to a point P vertically above Q by an inelastic string of length 2 meters. How high does the stone rise when the string is inclined at an angle 60o to the vertical?

A.

It does not rise

B.

2\(\sqrt{3}\) meters

C.

3 meters

D.

1 meter

E.

3

Correct answer is D

Cos 60o = \(\frac{PD}{2}\)

Cos 60o x 2 = 0.5 x 2

= 1m