WAEC Mathematics Past Questions & Answers - Page 226

1,126.
1,127.

In the diagram, PQRS is a circle center O. PQR is a diameter and ∠PRQ = 40°. Calculate ∠QSR

A.

30o

B.

40o

C.

45o

D.

50o

Correct answer is D

< Q = < R (OQ = OR = radii)

< QOR = 180° - 2(40°) = 100°

< QSR = < RPQ = \(\frac{1}{2}\) < QOR

= \(\frac{100}{2} = 50°\)

1,129.

The probabilities that Kodjo and Adoga pass an examination are \(\frac{3}{4}\) and \(\frac{3}{5}\) respectively. Find the probability of both boys failing the examination

A.

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

B.

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

C.

\(\frac{9}{20}\)

D.

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

Correct answer is A

P(Kodjo passing) = \(\frac{3}{4}\); P(Adoga passing) = \(\frac{3}{5}\)

P(Kodjo failing) = \(\frac{1}{4}\); P(Adoga failing) = \(\frac{2}{5}\)

P(both fail) = \(\frac{1}{4} \times \frac{2}{5}\)

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

1,130.

Calculate the standard deviation of the following marks; 2, 3, 6, 2, 5, 0, 4, 2

A.

1.5

B.

1.7

C.

1.8

D.

1.9

Correct answer is C

x 2 3 6 2 5 0 4 2 24
x - \(\bar{x}\) -1 0 3 -1 2 -3 1 -1  
\((x - \bar{x})^2\) 1 0 9 1 4 9 1 1 26

Mean = \(\frac{24}{8} = 3\)

Standard deviation = \(\sqrt{\frac{26}{8}}\)

= \(\sqrt{3.25}\)

= 1.802 \(\approeq\) 1.8