WAEC Mathematics Past Questions & Answers - Page 55

271.

Given that a = log 7 and b = \(\log\) 2, express log 35 in terms of a and b.

A.

a + b + 1

B.

ab - 1

C.

a - b + 1

D.

b - a + 1

Correct answer is C

\(\frac{\log 7 \times \log 10}{\log 2}\)

log 7 x log 10 \(\div\) log 2

a + 1 - b

a - b + 1

273.

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

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

274.

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

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

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

275.

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