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 7 of 10.
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.
Prakash said:
1 decade ago
From start of the calculation onwards we are taken only the reciprocal of the consumed quantity of petrol (i.e).
4000/7.5 = 533.33.
4000/8.00 = 500.
4000/8.5 = 470.58.
Total consumed petrol = 1503.91.
Finally to find avg litre of Petrol = Total amt spend for petrol/total consumed petrol. This is what krishna said in 2011.
4000/7.5 = 533.33.
4000/8.00 = 500.
4000/8.5 = 470.58.
Total consumed petrol = 1503.91.
Finally to find avg litre of Petrol = Total amt spend for petrol/total consumed petrol. This is what krishna said in 2011.
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