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Thread: Misc math problem

post 1639197923 05-22-2021, 04:27 PM
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Misc math problem

Forgive me for I am retard. I can't figure out how to solve this problem:



A tank can be filled by three pipesseparatelyin 20, 30, and 60 minutes respectively. In how many minutes can it be filled if all three pipes are filling the tanksimultaneously?

Multiple choice answers:
Spoiler!
14 minutes
12 minutes
10 minutes


I'm sure it's easy and the process is right under my nose, but I'm stumped
post 1639198123 05-22-2021, 04:32 PM
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I'll give you a hint brah

Rewrite each of the pipes as a rate.

Pipe 1 fills at a rate of 1/20 per minute
Pipe 2 fills at a rate of 1/30 per minute
Pipe 3 fills at a rate of 1/60 per minute

Whats the combined rate?
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post 1639198463 05-22-2021, 04:38 PM
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10 min bro
post 1639198553 05-22-2021, 04:40 PM
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Originally Posted By SaviorSelfJT⏩
I'll give you a hint brah

Rewrite each of the pipes as a rate.

Pipe 1 fills at a rate of 1/20 per minute
Pipe 2 fills at a rate of 1/30 per minute
Pipe 3 fills at a rate of 1/60 per minute

Whats the combined rate?
Yeah, so (1/20)x + (1/30)x + (1/60)x = 1

x (1/20 + 1/30 + 1/60) = 1

x = 1/(1/20 + 1/30 + 1/60)

x = 10
post 1639198573 05-22-2021, 04:40 PM
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Say a tank is 60 liters.

the 20 min one pumps 3 liter per minute.
the 30 min one pumps 2 liter per minute.
the 60 min one pumps 1 liter per minute.

combine it. 3+2+1 = 6.
6 liter per minute. How long to fill 60 liters? 10 minutes.
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post 1639198653 05-22-2021, 04:41 PM
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Originally Posted By SaviorSelfJT⏩
I'll give you a hint brah

Rewrite each of the pipes as a rate.

Pipe 1 fills at a rate of 1/20 per minute
Pipe 2 fills at a rate of 1/30 per minute
Pipe 3 fills at a rate of 1/60 per minute

Whats the combined rate?
damnit I knew it was going to be fairly simple. rept.
Originally Posted By nothingshocking⏩
10 min bro
yeah add 1/20 + 1/30 + 1/60 = 6/60 or 1/10 per minute. k den....
post 1639198943 05-22-2021, 04:45 PM
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Originally Posted By POTA⏩
Yeah, so (1/20)x + (1/30)x + (1/60)x = 1

x (1/20 + 1/30 + 1/60) = 1

x = 1/(1/20 + 1/30 + 1/60)

x = 10
See I never would have thought about doing it like that.
Originally Posted By backinthegymbro⏩
Say a tank is 60 liters.

the 20 min one pumps 3 liter per minute.
the 30 min one pumps 2 liter per minute.
the 60 min one pumps 1 liter per minute.

combine it. 3+2+1 = 6.
6 liter per minute. How long to fill 60 liters? 10 minutes.
or this.

I was thinking you had to do some work with ratios and percentages rather than simple fractions.
post 1639199013 05-22-2021, 04:47 PM
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Originally Posted By DolphinPilot⏩
or this.

I was thinking you had to do some work with ratios and percentages rather than simple fractions.
I'm legit retarded when it comes to math so don't take my way for it. It just happened to work because it's an easy number. It's not a mathematical formula.
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post 1639199903 05-22-2021, 05:00 PM
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10 minutes. Classic ratio problem brah.

Others have shown you how to get the answer.
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post 1639201223 05-22-2021, 05:19 PM
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Subtract the individual time from each to combine the gross time.

Pipe 2 takes 10 minutes more than the lowest time

Pipe 3 takes 40 minutes more than the lowest time

Lowest time is Pipe 1 at 20 minutes

20 + 10 + 40 = 70 minutes
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post 1639201673 05-22-2021, 05:25 PM
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Its always b
post 1639203283 05-22-2021, 05:49 PM
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