Originally Posted by Alexus

Well basically all you need to do is determine a few key things. 2 days is 48 hours and, in proportion to 2 days, 15 hours is 0.3125 days. What you need to do is put 15 over 48 and use x as a variable over 100. Now, you do 15 x 100 / 48 which will equal 31.25, which can be expressed as 31.25%. x = 31.25%. This is your percentage. Divide that by 100 and you will get 0.3125. This is your decimal. Your fraction will be 31.25 over 100, but in this case it is not feasible to express it as such because of the decimals. I think you can omit it.

Hope this helps. What you basically need to remember is this for percentages/proportions:


Btw, what grade are you in? The TI-89 is basically standard issue over here even in the advanced education calculus programs and you cannot take the course without purchasing one.