WAEC Mathematics Past Questions & Answers - Page 78

386.

Which of the following is used to determine the mode of a grouped data?

A.

Bar chart

B.

Frequency polygon

C.

Ogive

D.

Histogram

Correct answer is D

No explanation has been provided for this answer.

387.

Make K the subject of the relation T = \(\sqrt{\frac{TK - H}{K - H}}\)

A.

K = \(\frac{H(T^2 - 1)}{T^2 - T}\)

B.

K = \(\frac{HT}{(T - 1)^2}\)

C.

K = \(\frac{H(T^2 + 1)}{T}\)

D.

K = \(\frac{H(T - 1)}{T}\)

Correct answer is A

T = \(\sqrt{\frac{TK - H}{K - H}}\)

Taking the square of both sides, give

T2 = \(\frac{TK - H}{K - H}\)

T2(K - H) = TK - H

T2K - T2H = TK - H

T2K - TK = T2H - H

K(T2 - T) = H(T2 - 1)

K = \(\frac{H(T^2 - 1)}{T^2 - T}\)

388.

In the given diagram, \(\bar{QT}\) and \(\bar{PR}\) are straight lines, < ROS = (3n - 20), < SOT = n, < POL = m and < QOL is a right angle. Find the value of n.

A.

35o

B.

40o

C.

55o

D.

60o

Correct answer is A

In the diagram, QOR + 2m(vertically opposite angles)

So, m + 90° + 2m = 180°

(angles on str. line)

3m = 180° - 90°

3m = 90°

m = \(\frac{90^o}{3}\)

= 30°

substituting 30° for m in

2m + 4n = 200° gives

2 x 30° + 4n = 200°

60° + 4n = 200°

4n = 200° - 60°

= 140°

n = \(\frac{140°}{4}\)

= 35°

389.

If \(\frac{\sqrt{2} + \sqrt{3}}{\sqrt{3}}\) is simplified as m + n\(\sqrt{6}\), find the value of (m + n)

A.

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

B.

\(\frac{2}{3}\)

C.

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

D.

1\(\frac{2}{3}\)

Correct answer is C

\(\frac{\sqrt{2} + \sqrt{3}}{\sqrt{3}}\) = \(\frac{\sqrt{2} + \sqrt{3}}{\sqrt{3}}\) x \(\frac{\sqrt{3}}{\sqrt{3}}\)

= \(\frac{\sqrt{2} \times \sqrt{3} + \sqrt{3} \times \sqrt{3}}{\sqrt{3} \times \sqrt{3}}\)

= \(\frac{\sqrt{6} + 3}{3}\)

= \(\frac{3 + \sqrt{6}}{3}\)

= Hence, (m + n) = 1 + \(\frac{1}{3}\)


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

390.

Tom will be 25 years old in n years' time. If he is 5 years younger than Bade's present age.

A.

(30 - n)years

B.

(20 - n)years

C.

(25 - n)years

D.

(30 + n)years

Correct answer is A

Let Tom's present agr be x.

Then x = 25 - n

If Tom is 5 years younger than Bade, then Bade's present age is x + 5 = 25 - n + 5

= (30 - n)