Time in a fraction

Mr. Edward · #1 $Old$ 05-06-2008, 04:32 PM

my wants exact answers. We are multiplying speed by time, but I don't remember how to find the fractions of time. Like for example what would be the fraction for 1 hours and 15 mins?

TheEmptySet · #2 $Old$ 05-06-2008, 04:44 PM

Quote:

Originally Posted by Mr. Edward $View Post$

my wants exact answers. We are multiplying speed by time, but I don't remember how to find the fractions of time. Like for example what would be the fraction for 1 hours and 15 mins?

1 hour = 60 min

$\left( \frac{15 min}{1}\right) \left( \frac{1hr}{60 min}\right)=\frac{1}{4}hr$

$1hr+\frac{1}{4}hr=\frac{5}{4}hr$

o_O · #3 $Old$ 05-06-2008, 04:48 PM

If you want it in hours, you want to convert the 15 minutes into terms of hours. A trick is to find a conversion factor and multiply it with the 15 minutes. For example, you know that there are 60 minutes in one hour. This is your conversion factor: 60 min/hr. Now multiply it with 15 minutes such that the units cancel:

$15 \text{min} \cdot {\color{blue}\frac{1 \text{hour}}{60 \text{min}}} = \frac{15}{60} \text{hour} = \frac{1}{4}\text{hour}$

Note how the "min" cancels.

This works for anything else:
$73 \: \text{days} \cdot {\color{red} \frac{1 \: \text{year} }{365 \: \text{days} } } = \frac{1}{5} \: \text{years}$

Mr. Edward · #4 $Old$ 05-06-2008, 06:10 PM

thanks that helps