A bus 3

A bus has a petrol tank in the shape of a cylinder. The cylinder is 125 cm long and has a diameter of 42 cm.
(i) How much will a full tank of petrol cost at the rate of 5.23 per liter?
(ii) If the bus uses petrol at 12.5 liters for every 50 km, how far can the bus travel on a full tank of petrol?

Correct answer:

a =  905.7
x =  692.7 km

Step-by-step explanation:

$$\begin{gathered} h=125\text{cm} \\ D=42\text{cm} \\ r=D/2=42/2=21\text{cm} \\ {V}_1=\pi \cdot r^2\cdot h=3.1416\cdot 21^2\cdot 125\doteq 173180.295{\text{cm}}^3 \\ {V}_2=V_1\to \text{l}=V_1:1000\text{l}=173180.295:1000\text{l}=173.1803\text{l} \\ a=5.23\cdot V_2=5.23\cdot 173.1803=905.7 \end{gathered}$$

$x=\frac{50}{12.5}\cdot V_2=\frac{50}{12.5}\cdot 173.1803=692.7\text{km}$

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