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?
Answer: Option
Explanation:
| Total quantity of petrol consumed in 3 years |
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Total amount spent = Rs. (3 x 4000) = Rs. 12000.
 Average cost = Rs. |
 |
12000 x 51 |  |
= Rs. | 6120 | = Rs. 7.98 |
| 76700 | 767 |
Discussion:
93 comments Page 8 of 10.
Prakash said:
1 decade ago
From start of the calculation onwards we are taken only the reciprocal of the consumed quantity of petrol (i.e).
4000/7.5 = 533.33.
4000/8.00 = 500.
4000/8.5 = 470.58.
Total consumed petrol = 1503.91.
Finally to find avg litre of Petrol = Total amt spend for petrol/total consumed petrol. This is what krishna said in 2011.
4000/7.5 = 533.33.
4000/8.00 = 500.
4000/8.5 = 470.58.
Total consumed petrol = 1503.91.
Finally to find avg litre of Petrol = Total amt spend for petrol/total consumed petrol. This is what krishna said in 2011.
Sri said:
1 decade ago
Can't understand last calculation that why the reciprocal of the consumed quantity of the petrol is taken?
(1)
Akash said:
1 decade ago
Look the in the option two closet answer can be 8 or 7.98.
So either can be true but 8 is not possible because of it is not linear so answer will be 7.98.
So either can be true but 8 is not possible because of it is not linear so answer will be 7.98.
Gaurav dudeja said:
1 decade ago
What is its short trick?
Sathish said:
1 decade ago
Explain answers in short cut as much as possible.
Ash said:
1 decade ago
Thanks krishna...
Ganapathy said:
1 decade ago
What about this.
1yr 7. 50 * 4000 = 30000.
2yr 8. 00 * 4000 = 32000.
3yr 8. 50 * 4000 = 34000.
Total = 96000.
Total amount spend for 3yrs = 4000*3 = 12000.
Avg amt spent for 3 years = 96000/12000 = 8Rs.
1yr 7. 50 * 4000 = 30000.
2yr 8. 00 * 4000 = 32000.
3yr 8. 50 * 4000 = 34000.
Total = 96000.
Total amount spend for 3yrs = 4000*3 = 12000.
Avg amt spent for 3 years = 96000/12000 = 8Rs.
(1)
Nitin said:
1 decade ago
Thnks krishna your result is so easy.
Longanathan said:
1 decade ago
Thanks Krish, that was simple and sound.
Saikumar said:
1 decade ago
Thanks krish.
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