WAEC - Mathematics (2023 - No. 23)
An empty cylindrical tank is 140 cm in diameter. If 200 litres of water was poured into the tank. Calculate, correct to the nearest centimeter, the height of the water in the tank. (\(Take \pi = \frac{22}{7})\)
91cm
7cm
13cm
57cm
Magyarázat
given that diameter = 140cm ⇒radius = 70cm, volume of cylinder = 200litres = \(200,000cm^3\)
volume of cylinder = base area times height = \(\pi r^2h\)
\( 200,000cm^3 = \frac{22}{7} \times 70 \times 70 \times h\)
\(200,000 = \frac{107,800h}{7}\)
cross multiply
1,400,000 = 107,800h
\( h = \frac{1,400,000}{107,800}\)
= 13cm (to the nearest cm).