WAEC Mathematics Past Questions & Answers - Page 104

516.

Simplify \(\frac{1\frac{7}{8} \times 2\frac{2}{5}}{6\frac{3}{4} \div \frac{3}{4}}\)

A.

90o

B.

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

C.

2

D.

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

Correct answer is D

\(\frac{1\frac{7}{8} \times 2\frac{2}{5}}{6\frac{3}{4} \div \frac{3}{4}}\)

from numerator \(1 \frac{7}{8} \times 2 \frac{2}{5}\)

= \(\frac{15}{8} \times \frac{12}{5}\)

= \(\frac{3 \times 3}{2 \times 1} = \frac{9}{2}\)

from denominator \(6\frac{3}{4} \div \frac{3}{4}\)

= \(\frac{27}{4} \div \frac{3}{4}\)

= \(\frac{27}{4} \times \frac{4}{3}\)

= \(\frac{9 \times 1}{1 \times 1} = \frac{9}{1}\)

\(\frac{9}{2} \div \frac{9}{1} = \frac{9}{2} \times \frac{1}{9}\)

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

517.

In what number base is the addition 465 + 24 + 225 = 1050?

A.

ten

B.

nine

C.

eight

D.

seven

Correct answer is D

No explanation has been provided for this answer.

518.

If 9(2 - x) = 3, find x

A.

1

B.

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

C.

2

D.

\(\frac{5}{2}\)

Correct answer is B

9(2 - x) = 3

32(2 - x) = 3

2(2 - x) = 1

4 - 2x = 1

-2x = 1 - 4

-2x = -3

x = \(\frac{-3}{-2}\)

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

519.

Multiply 2.7 x 10-4 by 6.3 x 106 and leave your answers in standard form

A.

1.7 x 103

B.

1.70 x 103

C.

1.701 x 103

D.

17.01 x 103

Correct answer is C

2.7 x 10-4 x 6.3 x 106

= 2.7 x 6.3 x 10-4 x 106

= 17.01 x 10-4 + 6

= 17.01 x 102

= 1.701 x 101 x 102

= 1.701 x 101 + 2

= 1.701 x 103

520.

The diagram is a polygon. Find the largest of its interior angles

A.

300o

B.

100o

C.

120o

D.

150o

Correct answer is D

Sum of interior angles = 3602

i.e 3x + 2x + 2x + x + 4x = 360o

12x = 360

x = \(\frac{360}{12}\)

x = 30o

x + c = 180

30o + c = 180

c = 180 - 30

c = 150o