WAEC Mathematics Past Questions & Answers - Page 119

591.

Factorize the expression: am + bn - an - bm

A.

(a - b)(m + n)

B.

(a - b)(m - n)

C.

(a + b)(m - n)

D.

(a + b)(m + n)

Correct answer is B

am + bn - an - bm am - an - bm + bn a(m - n) - b(m - n) (a - b)(m - n)

592.

The height of a cylinder is equal to its radius. If the volume is 0.216 \(\pi\) m\(^3\). Calculate the radius.

A.

0.46m

B.

0.60m

C.

0.87m

D.

1.80m

Correct answer is B

volume of cylinder = \(\pi r^2\)h

0.216\(\pi\) m\(^3\) = \(\pi \times r^2 \times h\)

Since r = h,

0.216 = r\(^3\)

r\(^3\) = 0.216

r = \(\sqrt[3]{0.216}\)

= 0.6

593.

What is the value of 3 in the number 42.7531?

A.

\(\frac{3}{10000}\)

B.

\(\frac{3}{1000}\)

C.

\(\frac{3}{100}\)

D.

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

Correct answer is B

No explanation has been provided for this answer.

594.

The length of a piece of stick is 1.75m. A girl measured it as 1.80m. Find the percentage error

A.

\(\frac{28}{7}\)%

B.

\(\frac{29}{7}\)%

C.

5%

D.

\(\frac{20}{7}\)%

Correct answer is D

Error = 1.80m - 1.75m = 0.05m

%error = \(\frac{\text{error}}{\text{true measurement}}\) x 100%

595.

The perimeter of a sector of a circle of radius 4cm is (\(\pi + 8\))cm. Calculate the anle of the sector

A.

45o

B.

60o

C.

75o

D.

90o

Correct answer is A

Perimeter of sector = 2r + \(\frac{\theta}{360^o} \times 2\pi r\)

\(\pi + 8 = 2 \times 4 + \frac{\theta}{3360^o} \times 2 \pi \times 4\)

\(\pi + 8 + \frac{\theta}{360^o} \times 8 \pi\)

P + 8 - 8 = \(\frac{\theta \pi}{456o}\)

\(\pi = \frac{\theta \pi}{45^o}\)

\(\theta \pi = 45^o\)