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:
92 comments Page 3 of 10.
Md. Sah-alam said:
6 years ago
Approximate cost should be 8.
Raya said:
6 years ago
If you do (7.50+8+8.50)÷3 then you just get the avg per litre cost, but not the average of your spending.
In this question, we need to find the per lit avg cost of your spending you spend Rs 4000. Diff ppl have different avg per litre cost. It depends on how many litres you have used so hence we need to find the litre or amt you have consumed each year.
So, in the last step, we divide the total cost of 3 yrs by total amt of 3 years to GET THE PER LITRE COST OF 3 YEARS WHICH IS NOTHING BUT THE AVERAGE OF 3 YEARS.
In this question, we need to find the per lit avg cost of your spending you spend Rs 4000. Diff ppl have different avg per litre cost. It depends on how many litres you have used so hence we need to find the litre or amt you have consumed each year.
So, in the last step, we divide the total cost of 3 yrs by total amt of 3 years to GET THE PER LITRE COST OF 3 YEARS WHICH IS NOTHING BUT THE AVERAGE OF 3 YEARS.
Shubham said:
6 years ago
In this equation,
= 4000(2/15+1/8+2/17),
= 76700/51.
= 4000(2/15+1/8+2/17),
= 76700/51.
Dokuparthi Brahmam said:
6 years ago
Thanks @Krishna.
Shivani Sharma said:
6 years ago
Thanks @Krishna.
Arjun said:
7 years ago
7.50/3 + 8/3 + 8.50/3
= 2.5+2.66+2.83 = 7.9.
= 2.5+2.66+2.83 = 7.9.
(5)
Satya said:
7 years ago
It is very easy to understand. Thanks for solving @Krishna.
Shanmukh Adari said:
7 years ago
It was so useful, thanks for the answer @M.V.Krishna.
Aman said:
7 years ago
1st-year cost of petrol=7.50.
2nd-year cost of petrol=8.
3rd-year cost of petrol=8.50.
The spend amounts each year=4000.
1st-year the quantity of petrol used =4000/7.50=533.33,
2nd yr = 4000/8=500,
3rd yr=4000/8.50=503.33,
total amount spend = 4000 * 3/quantity of petrol use.
12000/1536.66 = 7.9.
2nd-year cost of petrol=8.
3rd-year cost of petrol=8.50.
The spend amounts each year=4000.
1st-year the quantity of petrol used =4000/7.50=533.33,
2nd yr = 4000/8=500,
3rd yr=4000/8.50=503.33,
total amount spend = 4000 * 3/quantity of petrol use.
12000/1536.66 = 7.9.
Lavina said:
7 years ago
Nice one, it's really helpful, thanks @M. V. Krishna.
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