Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 9)
9.
Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?
Answer: Option
Explanation:
| Part filled by A in 1 min = | 1 | . |
| 20 |
| Part filled by B in 1 min = | 1 | . |
| 30 |
| Part filled by (A + B) in 1 min = |  |
1 | + | 1 |  |
= | 1 | . |
| 20 | 30 | 12 |
Both pipes can fill the tank in 12 minutes.
Discussion:
15 comments Page 1 of 2.
Mahadev said:
1 decade ago
How 1/12 is coming please explain?
Ramkumar said:
1 decade ago
1/20 + 1/30 = 2/50 so = 1/25.
Then how it is possible of 1/12.
Then how it is possible of 1/12.
Sanjana said:
1 decade ago
LCM of 20 and 30 is 60.
Solve,
1/20+1/30.
= 3+2/60.
= 5/60.
= 1/12.
Solve,
1/20+1/30.
= 3+2/60.
= 5/60.
= 1/12.
Karthik said:
1 decade ago
How did you get (1/20+1/30)+1/12?
Jigme wangdi said:
1 decade ago
How comes 3+2?
Priya said:
10 years ago
(1/20 + 1/30) = In order to add both of these fractions first make sure whether the denominator of those two fractions are same. Here the denominators are different.
Cross multiply the two fraction:
= (30+20)/(30*20) = 50/600 = 1/12.
Cross multiply the two fraction:
= (30+20)/(30*20) = 50/600 = 1/12.
Surya sjv said:
9 years ago
Average of these (20+30) / 2 = 25.
Why this is wrong aspect please tell me the reason sir.
Why this is wrong aspect please tell me the reason sir.
Myousry said:
9 years ago
Why therefore both pipes can fill the tank in 12 mins?
Prawesh Pradhan said:
9 years ago
By applying formula,
=> x * y/x + y,
=> 20 * 30/20 + 30,
=> 600/50 = 12.
=> x * y/x + y,
=> 20 * 30/20 + 30,
=> 600/50 = 12.
Hawdhaa said:
9 years ago
Thank you for explaining the solution.
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