(a) \(\frac{15.05 \times \sqrt{0.00695}}{6.95 \times 10^{2}}\)

No	Log
15.05	\(1.1775 = 1.1775\)
\(\sqrt{0.00695}\)	\(\bar{3}.8420 \div 2 = \bar{2}.9210\)
	= 0.0985
\(6.95 \times 10^{2}\)	- 2.8420
Antilog = 0.001805	= \(\bar{3}.2565\)

\(\therefore \frac{15.05 \times \sqrt{0.00695}}{6.95 \times 10^{2}} \approxeq 0.00181\) (3 sig. figs)
(b) No of boys = 2, No of girls = 3
\(\therefore\) Total students = 5
(i) P(both are boys) = \(\frac{2}{5} \times \frac{1}{4} = \frac{1}{10}\)
(ii) P(both are of different sexes) = P(first a boy, then a girl) or P(first a girl, then a boy)
= \(\frac{2}{5} \times \frac{3}{4} + \frac{3}{5} \times \frac{2}{4} \)
= \(\frac{6}{20} + \frac{6}{20}\)
= \(\frac{12}{20} = \frac{3}{5}\)