SOLUTION: if 2 persons take 2 hours to make 1 table and 4 persons make 4 tables in how many hours?

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First way to work it:

2 persons will take 4 times as long, or 8 hours, to make 4 tables as they take
to make 1 table.

Twice as many people or 4 persons will only take half as long as 2 persons take
to make 4 tables.  So it will take them 4 hours.

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Second way to work it:

1 person will take twice as long as 2 persons, or 4 hours to make 1 table

4 persons will take 4 hours to make 4 tables.

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Third way to work it:

To make four times as many tables in 2 hours will take 4 times as many people
or 8 people.

So with only 4 people it will take twice as long as with 8 people, so it will
take them 4 hours.

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Fourth way to work it:

Use the worker-time-job formula, which is:



where

W1 = the number of workers in the first situation.
T1 = the number of time units (hours in this case) in the first
situation.
J1 = the number of jobs in the first situation.

W2 = the number of workers in the second situation.
T2 = the number of time units (hours in this case) in the second
situation.
J2 = the number of jobs in the second situation.

W1 = 2             W2 = 4     
T1 = 2             T2 = ? 
J1 = 1             J2 = 4






 
    4 = T2

Answer 4 hours

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Edwin