WAEC Past Questions and Answers - Page 3927

19,631.

A known weight of soil sample was oven-dried to obtain a constant weight. The loss in weight was due to
loss of 

A.

organic matter only

B.

water only

C.

water and organic matter

D.

inorganic matter and water

Correct answer is C

No explanation has been provided for this answer.

19,632.

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

19,635.

In the diagram, AB is a vertical pole and BC is horizontal. If |AC| = 10m and |BC| = 5m, calculate the angle of depression of C from A

A.

63o

B.

60o

C.

45o

D.

27o

Correct answer is B

In triangle ABC, \(\frac{BC}{AC} = \cos \theta\)

\(\implies \cos \theta = \frac{5}{10} = 0.5\)

\(\theta = \cos^{-1} (0.5) = 60°\)