The rate of consumption of petrol by a vehicle varies directly as the square of...
MATHEMATICS
WAEC 2015
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: A. 22\(\frac{1}{2}\)km
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
Post an Explanation Or Report an Error
If you see any wrong question or answer, please leave a comment below and we'll take a look. If you doubt why the selected answer is correct or need additional more details? Please drop a comment or Contact us directly. Your email address will not be published. Required fields are marked *