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 6 of 10.
Ashwini madne said:
9 years ago
@Santhosh Sandy.
= 4000/7.50 + 4000/8 + 4000/8.50.
= 4000(1/7.50 + 1/8 + 1/8.50) ...... 1/7.50.
It can be written as 100/750 which is equal to 2/15 same as 1/8.50 can be written as 100/850 which is equal to 2/17.
= 4000(2/15 + 1/8 + 2/17).
= 4000[{(2 * 8) + (15 * 1)/15 * 8} + 2/17].
= 4000[{31/120 + 2/17}].
= 4000[767/2040].
= 76700/51.
= 4000/7.50 + 4000/8 + 4000/8.50.
= 4000(1/7.50 + 1/8 + 1/8.50) ...... 1/7.50.
It can be written as 100/750 which is equal to 2/15 same as 1/8.50 can be written as 100/850 which is equal to 2/17.
= 4000(2/15 + 1/8 + 2/17).
= 4000[{(2 * 8) + (15 * 1)/15 * 8} + 2/17].
= 4000[{31/120 + 2/17}].
= 4000[767/2040].
= 76700/51.
(1)
Santhosh Sandy said:
9 years ago
In the solution how they got 4000(2/15+1/8+2/17) = (76700/51) ?
I'm bit confused :-(.
I'm bit confused :-(.
Henry said:
10 years ago
When you say approximately. Is it wise to say the answer is 7.98 instead of 8.0 which is B?
Mounika said:
10 years ago
Answer: 1503.92.
Subhasmita said:
10 years ago
Please solve this equation 4000(2/15+1/8+2/17) = ?
Jeevan j said:
10 years ago
At most one minute is the time available for this question. So further simplifications is required.
Gameruler said:
10 years ago
How can we calculate this without using the calculator?
Abhishek said:
1 decade ago
Where 51 came from?
Gunwanti said:
1 decade ago
Can any one explain 76700/51?
Jobin said:
1 decade ago
Normally average will be Rs. 8 if we won't take the factor of Rs. 4000 per year. When we consider the amount per year, number of liter consumed in the 1st year will be more than second and third.
So approximately the average will be less than 8 and greater than 7.5. And more nearer to 8. So the answer is 7.98.
So approximately the average will be less than 8 and greater than 7.5. And more nearer to 8. So the answer is 7.98.
(1)
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