The rate of consumption of petrol by a vehicle varies directly as the square of the distance covered. If 4 litres of petrol is consumed on a distance of 15km. how far would the vehicle go on 9 litres of petrol?
-
A.
22(frac{1}{2})km -
B.
30km -
C.
33(frac{1}{2})km -
D.
45km
Correct Answer: Option A
Explanation
R (alpha) D2
R = D2K
R = 4 Litres when D = 15cm
thus; 4 = 152k
4 = 225k
k = (frac{4}{225})
This gives R = (frac{4D^2}{225})
Where R = 9litres
equation gives
9 = (frac{4D^2}{225})
9 x 225 = 4d2
D2 = (frac{9 times 225}{4})
D = (sqrt{9 times 225}{4})
= (frac{3 times 15}{2})
= 22(frac{1}{2})km