<PRE><B>Question 368955</B>
an electrician requires 65 min to install a ceiling fan. The electrican and an apprentice working together take 40 min to install the fan. How long would it take the apprentice working alone to install the ceiling fan? 
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Electrician rate: 1/65 job/min
Together rate:::: 1/40 job/min
Aprentice rate::: 1/x job/min
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Equation:
rate + rate = together rate
1/65 + 1/x = 1/40
Multiply thru by 40*65x to get:
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40x + 40*65 = 65x
25x = 40*65
25x = 2600
x = 2600/25
x = 104 minutes (time the apprentice would need)
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Cheers,
Stan H.</PRE>