2005 - WAEC Mathematics Past Questions and Answers - page 5

Area of a sector (=\frac{\theta}{360}\times \pi r^2<br /> \left(\frac{144}{360}\times \pi \times \frac{3.5}{1} \times 3.5\right)cm^2 = 4.9\pi cm^2)

Volume of rectangular packet = (16 x 12 x 6)cm³ = 1152cm³. Volume of cube of sugar = 2 x 2 x 2 = 8cm
∴ The number of cubes f sugar (=\frac{1152}{8}=144)

(y \propto \frac{1}{x^2} \Rightarrow y = \frac{k}{x^2} \Rightarrow k = yx^2<br /> k = 1\frac{1}{4} \times 4^2 \Rightarrow k=\frac{5}{4}\times \frac{16}{1}=20<br /> ∴y = 20 \div \left(\frac{1}{2}\right)^2=20\times \frac{4}{1}=80)

The car was sold at 96% ---- N84,000.00
The price of the car is 100% ---- ?
(\frac{100}{96} \times \frac{84,000}{1}; 25 \times 10,500 = 87,500 )

(% increase = \frac{Increase}{initial\hspace{1mm} salary}\times 100%<br /> Increase=N3,200 - N2,700 = N500<br /> Initial \hspace{1mm} salary=N2,700.00=\frac{N500}{N2,700}\times 100% = 18.5%)

Reflex + ∠OML + ∠ONL + ∠NLM = 360
280^o + 10^o + 15^o + x = 360^o => 305^o + x^o = 360^o
x = 360^o - 305^o = 55^o