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 2 of 10.
Rajeshwar Singh said:
8 years ago
Hi, everyone the best way to solve the equation is we having value 7.50, 8, 8.50.
For those value whose in the decimal format we wl divide by as per req we wl divide 7.50/100 and there is no need for 8 wl do for 8.50/100 nw we calculate like that 4000(1/7.5+1/8+1/8.5).
4000(100/7.5+1/8+100/8.5).
This will get the value.
For those value whose in the decimal format we wl divide by as per req we wl divide 7.50/100 and there is no need for 8 wl do for 8.50/100 nw we calculate like that 4000(1/7.5+1/8+1/8.5).
4000(100/7.5+1/8+100/8.5).
This will get the value.
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)
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.
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.
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)
Krishna said:
6 years ago
See at last everyone is asking why they have taken reciprocal. The answer is that in the question itself they asked what is the average cost per liter. So we have to find the cost of the amount of petrol not petrol at cost.
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)
Chippey said:
1 decade ago
After taking 4000 as common it is left with.
4000[1/7.50 + 1/8 + 1/8.50].
1/7.50 can be written as 100/750 which is equal to 2/15.
Similarly 1/8.50 can be written as 100/850 which is equal to 2/17.
4000[1/7.50 + 1/8 + 1/8.50].
1/7.50 can be written as 100/750 which is equal to 2/15.
Similarly 1/8.50 can be written as 100/850 which is equal to 2/17.
Sneha said:
4 years ago
= 4000( 100/750) + (1/8) + (100/850).
= 4000(2/15+1/8+2/17) cross multiplication,
= 4000(31/120+2/17) Cross mul,
= 4000(767/2040),
= 3068000/2040 decided by 4 on both side,
= 76700/51.
= 4000(2/15+1/8+2/17) cross multiplication,
= 4000(31/120+2/17) Cross mul,
= 4000(767/2040),
= 3068000/2040 decided by 4 on both side,
= 76700/51.
(2)
Nitesh bhati said:
1 decade ago
1st year 4000/7.5 = 533.3.
2nd year 4000/8 = 500.
3rd year 4000/8.50 = 470.5.
= 533.3+500+470.5 = 1503.8.
= 1503.8*7.98 = 4000*3.
= 12000 = 12000.
LHS = RHS.
2nd year 4000/8 = 500.
3rd year 4000/8.50 = 470.5.
= 533.3+500+470.5 = 1503.8.
= 1503.8*7.98 = 4000*3.
= 12000 = 12000.
LHS = RHS.
(1)
Prini said:
1 decade ago
Here the question is cost per litre.
So ans = (total cost for 3 years)/(total litres consumed)
= (4000*3)/total petrol litres consumed.
this is the logic.
So ans = (total cost for 3 years)/(total litres consumed)
= (4000*3)/total petrol litres consumed.
this is the logic.
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