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 8 of 10.

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.

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.
(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.

Karuna said:   1 decade ago
Other than this any other simple calculation is there ?


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