WAEC Mathematics Past Questions & Answers - Page 92

456.

\(\begin{array}{c|c}height & 2 & 3 & 4 & 5 & 6 \\ \hline frequency & 2 & 4 & 5 & 3 & 1
\end{array}\)
The table shows the distribution of the height of plants in a nursery. Calculate the mean height of the plants.

A.

3.8

B.

3.0

C.

2.8

D.

2.3

Correct answer is A

\(\begin{array}{c|c} height(x) & frequency(f) & fx \\ \hline 2 & 2 & 4\\ 3 & 4 & 12\\ 4 & 5 & 20 \\ 5 & 3 & 15\\ 6 & 1 & 6\end{array}\)

mean\(\bar{x} = \frac{\sum fx}{\sum f}\)

= \(\frac{57}{15}\)

= 3.8

457.

If (x - a) is a factor pf bx - ax + x2, find the other factor.

A.

(x + b)

B.

(x - b)

C.

(a + b)

D.

(a - b)

Correct answer is A

No explanation has been provided for this answer.

458.

Find the gradient of the line joining the points (2, -3) and 2, 5)

A.

9

B.

1

C.

2

D.

undefined

Correct answer is D

(2, -3)(2, 5)

gradient = \(\frac{y_ = y_1}{x_2 = x_1} = \frac{5 - (-3)}{2 - 2}\)

= \(\frac{5 + 3}{0}\)

= \(\frac{8}{0}\)

= undefined

459.

F x varies inversely as y and y varies directly as Z, what is the relationship between x and z?

A.

x \(\alpha\) z

B.

x \(\alpha \frac{1}{z}\)

C.

x \(\alpha z^2\)

D.

x \(\alpha \frac{1}{z^2}\0

Correct answer is B

x \(\alpha \frac{1}{y}\)

y \(\alpha z\)

the relationship = x \(\alph \frac{1}{z}\)

460.

Make u the subject of formula, E = \(\frac{m}{2g}\)(v2 - u2)

A.

u = \(\sqrt{v^2 - \frac{2Eg}{m}}\)

B.

u = \(\sqrt{\frac{v^2}{m} - \frac{2Eg}{4}}\)

C.

u = \(\sqrt{v- \frac{2Eg}{m}}\)

D.

u = \(\sqrt{\frac{2v^2Eg}{m}}\)

Correct answer is A

E = \(\frac{m}{2g}\)(v2 - u2)

multiply both sides by 2g

2Eg = 2g (\(\frac{M}{2g} (V^2 - U^2)\)

2Eg = m(V2 - U2)

2Eg - mV2 - mU2

mU2 = mV2 - 2Eg

divide both sides by m

\(\frac{mU^2}{m} = \frac{mV^2 - 2Eg}{m}\)

U2 = \(\frac{mV^2 - 2Eg}{m}\)

= \(\frac{mV^2}{m} - \frac{2Eg}{m}\)

U2 = V2 - \(\frac{2Eg}{m}\)

U = \(\sqrt{V^2 - \frac{2Eg}{m}}\)