WAEC Mathematics Past Questions & Answers - Page 55

272.

The ages of Tunde and Ola are in the ratio 1:2. If the ratio of Ola's age to Musa's age is 4:5, what is the ratio of Tunde's age to Musa's age?

A.

1 : 4

B.

1 : 5

C.

2 : 5

D.

5 : 2

Correct answer is C

Tunde: Ola \(\to\) 1 : 2 ; Ola; Musa \(\to\) 4 : 5

\(\frac{1}{2}\) x \(\frac{4}{5}\)

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

273.

Evaluate \(\frac{3\frac{1}{4} \times 1\frac{3}{5}}{11\frac{1}{3} - 5 \frac{1}{3}}\)

A.

\(\frac{14}{15}\)

B.

\(\frac{13}{15}\)

C.

\(\frac{4}{5}\)

D.

\(\frac{11}{15}\)

Correct answer is B

\(\frac{3\frac{1}{4} \times 1\frac{3}{5}}{11\frac{1}{3} - 5 \frac{1}{3}}\) = \(\frac{\frac{26}{5}}{\frac{18}{3}}\) = \(\frac{26}{5} \div \frac{18}{3}\)

= \(\frac{13}{15}\)

274.

If x varies inversely as y and y varies directly as z, what is the relationship between x and z?

A.

x \(\alpha\) z

B.

x \(\alpha\) \(\frac{1}{z}\)

C.

a \(\alpha\) z\(^2\)

D.

x \(\alpha\) \(\frac{1}{z^2}\)

Correct answer is B

\(x \propto \frac{1}{y}\), y \(\propto\) z

x = \(\frac{k}{y}\)

y = mz

Since y = mz,

x = \(\frac{k}{mz}\), where k and m are constants. Hence,

x \(\propto\) \(\frac{1}{z}\)

275.

Express 0.0000407, correct to 2 significant figures

A.

0.0

B.

0.00004

C.

0.000041

D.

0.0000407

Correct answer is C

0.0000407 to 2 s.f 0.000041 (2 s.f)