SOLUTION: Miguel works 1.5 times faster than Maria. Together, they do a job in 7.5 hours. How long does it take Maria working alone to do the same job?

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Question 1193704: Miguel works 1.5 times faster than Maria. Together, they do a job in 7.5 hours. How long does it take Maria working alone to do the same job?
Answer by ikleyn(52806) About Me  (Show Source):
You can put this solution on YOUR website!
.

I read your post this way 

    Miguel works 1.5 times  highlight%28cross%28faster_than%29%29  highlight%28as_fast_as%29  Maria. Together, they do a job in 7.5 hours. 
    How long does it take Maria working alone to do the same job?


The other form, which you use in your post, is ambiguous in English and may lead to more than one interpretations.
THEREFORE, that form is not recommended to use in Math problems for English speakers/readers. 


Let x be Maria's rate of work (in jobs per hour)

Then Miguel's rate of work is 1.5x jobs per hour.


Their combined rate of work is the sum  x + 1.5x = 2.5x jobs per hour.


It means that  2.5x = 1%2F7.5,  or  x = 1%2F%287.5%2A2.5%29 = 4%2F%2815%2A5%29 = 4%2F75  jobs per hour.


Hence, Maria needs  75%2F4 = 183%2F4 hours = 18 hours and 45 minutes to do the job alone.    ANSWER

Solved.


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In English, this phrase 

    "Miguel works 1.5 times faster than Maria. "

works differently than its analogues in other languages.


It works differently, its meaning is different, it carries different meaning and it is understood differently.


Newcomers usually don't know about it . . . until somebody will explain them . . .