Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 6)
6.
Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is:
Answer: Option
Explanation:
| Work done by the waste pipe in 1 minute = | 1 | - |  |
1 | + | 1 |  |
| 15 | 20 | 24 |
| = | |
1 | - | 11 | |
| 15 | 120 |
| = - | 1 | . [-ve sign means emptying] |
| 40 |
 Volume of |
1 | part = 3 gallons. |
| 40 |
Volume of whole = (3 x 40) gallons = 120 gallons.
Discussion:
48 comments Page 4 of 5.
Zonked said:
2 decades ago
i dont get this one.
S.n.raju said:
1 decade ago
Given,
First pipe takes 20h.
Second pipe take 24h.
ALL together take 15h.
Assuming that capacity of tank L. C. M [20, 24, 15] = 120.
First pipe can fill 6u/m.
Second pipe fill 5u/m.
All three fill 8u/m -------> 1.
First and second together fill in 11m/u----------> 2.
From 1 and 2 we get;
Third pipe fills the tank in 3u/m that is 120/3 = 40u of total fill.
But given 3 gallons are empty.
3 * 40 = 120gallons (capacity of tank).
First pipe takes 20h.
Second pipe take 24h.
ALL together take 15h.
Assuming that capacity of tank L. C. M [20, 24, 15] = 120.
First pipe can fill 6u/m.
Second pipe fill 5u/m.
All three fill 8u/m -------> 1.
First and second together fill in 11m/u----------> 2.
From 1 and 2 we get;
Third pipe fills the tank in 3u/m that is 120/3 = 40u of total fill.
But given 3 gallons are empty.
3 * 40 = 120gallons (capacity of tank).
Dwarikesh Sharma said:
1 decade ago
(1/20)+(1/24)-3G = (1/15).
-3G = (1/15)-(1/20+1/24).
-3G = -3/120.
G = 1/120.
Capacity of Tank G=120 gallon.
-3G = (1/15)-(1/20+1/24).
-3G = -3/120.
G = 1/120.
Capacity of Tank G=120 gallon.
Sujit baji said:
1 decade ago
(1/15 - 11/120) = -1/40 how? please explain it.
Ragi said:
1 decade ago
15(x/20+x/24-3) = x.
(11x-120)/8 = x.
x = 40 gallon.
(11x-120)/8 = x.
x = 40 gallon.
Aniket said:
1 decade ago
You can simply take the L.C.M of the values and get the result.
L.C.M of above values = 2x2x2x3x5 = 120.
L.C.M of above values = 2x2x2x3x5 = 120.
Sreeram said:
1 decade ago
A and B.
Time: 20min and 24min.
Efficiency: 6 and 5.
Work done A+B in 1 min = 11.
Work done A+B in 15 min = 11*15 = 165.
Tank emptied by C in 15 min = 45.
= 165 - 45 = 120 gallons.
Time: 20min and 24min.
Efficiency: 6 and 5.
Work done A+B in 1 min = 11.
Work done A+B in 15 min = 11*15 = 165.
Tank emptied by C in 15 min = 45.
= 165 - 45 = 120 gallons.
Snhk said:
1 decade ago
L.C.M of 20, 15, 24 = 120 unit total capacity.
1st pipe = 6 unit.
2nd pipe = 5 unit.
= 11 unit.
Total 120/15 = 8 unit.
3rd (-) pipe capacity = (11 - 8) = 3 unit.
As UTC 120.
3rd pipe can empty = 120/3 = 40 unit which is = 3 gallons per minute.
Hence the capacity of the tank (40*3) =120 gallons.
1st pipe = 6 unit.
2nd pipe = 5 unit.
= 11 unit.
Total 120/15 = 8 unit.
3rd (-) pipe capacity = (11 - 8) = 3 unit.
As UTC 120.
3rd pipe can empty = 120/3 = 40 unit which is = 3 gallons per minute.
Hence the capacity of the tank (40*3) =120 gallons.
Nitin said:
1 decade ago
L.C.M of 20, 15, 24 = 120 unit total capacity.
120/3 = 40.
40 * 3 = 120.
120/3 = 40.
40 * 3 = 120.
Sindhu said:
1 decade ago
Why making the values in the ratio one we get.
C = 1/15 - (1/20 + 1/24).
C = 1/15 - (1/20 + 1/24).
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