Question 1191073
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Fred can seal asphalt driveway in 1/3 the time it takes John. 
Working together, it takes them 1 1/2 hours. How long would it have taken Fred working alone?
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            This problem can be solved  MENTALLY,  without using equation,

            by applying reasoning and common sense.



<pre>
The problem says that Fred works as productive, as 3 instanses of John.


Next, the problem says that working together, they complete the job in 1.5 hours.


It is the same as to say that 4 instances of John will complete the job in 1.5 hours.


Hence, John alone will do the job in 4*1.5 = 6 hours.


It implies that Fred, working 3 times as fast as John, will complete the job in 6:3 = 2 hours.    <U>ANSWER</U>
</pre>

Solved  &nbsp;&nbsp;&nbsp;&nbsp;//  &nbsp;&nbsp;&nbsp;&nbsp;mentally.