Aptitude - Average - Discussion

Discussion Forum : Average - General Questions (Q.No. 9)
9.
A car owner buys petrol at Rs.7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year?
Rs. 7.98
Rs. 8
Rs. 8.50
Rs. 9
Answer: Option
Explanation:

Total quantity of petrol
consumed in 3 years
= 4000 + 4000 + 4000  litres
7.50 8 8.50
= 4000 2 + 1 + 2  litres
15 8 17
= 76700  litres
51

Total amount spent = Rs. (3 x 4000) = Rs. 12000.

Average cost = Rs. 12000 x 51 = Rs. 6120   = Rs. 7.98
76700 767

Discussion:
92 comments Page 10 of 10.

Saimadhav Thottala said:   2 years ago
1st year = 4000/7.5 = 533.33 litres,
2nd year = 4000/8 = 500 litres,
3rd year = 4000/8.5 = 470.58 litres.

Total Petrol in 3 years = 1503.91 litres
Total amount invested in 3 year = 4000 * 3 = 12000,
Average cost of petrol per litre = 12000/1503.91 = 7.98 Rs.
(175)

Swetha S said:   5 months ago
Average cost = 7.50/3 + 8/3 + 8.50/3.
Average cost = 2.50 + 2.66 + 2.83 = 7.99.
(51)


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