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 7 of 10.
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)
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)
Ramsreeram said:
1 decade ago
Its simple because answer must be close to 7.98 or 8 here averages so it must be ratio form so 7.98.
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.
Smiley said:
1 decade ago
Can anyone explain this 2/15+1/8+2/17 how it is?
Smiley said:
1 decade ago
How it comes 2/15 + 1/8 + 2/17?
(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.
Lalli said:
1 decade ago
Why the 5/18 is divided often, and it can be explained briefly.
Rabindra gouda said:
1 decade ago
Most simply answer:
Total amount of rupees/total amount of petrol in litre
3yrs total spent petrol in rupees = 3*4000 = 12000 ........(i).
Total amount of petrol spent in 3year = (4000/7.50)+(4000/8)+(4000/8.50)..........(ii).
Equation (i)divided by equation(ii) we get avg rupees spent per petrol
12000/533.3+500+470.5 = 12000/1503.8 = 7.98(answer).
Total amount of rupees/total amount of petrol in litre
3yrs total spent petrol in rupees = 3*4000 = 12000 ........(i).
Total amount of petrol spent in 3year = (4000/7.50)+(4000/8)+(4000/8.50)..........(ii).
Equation (i)divided by equation(ii) we get avg rupees spent per petrol
12000/533.3+500+470.5 = 12000/1503.8 = 7.98(answer).
Chilo said:
1 decade ago
Why not choosing 8 as answer? Please explain.
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