Prep. for COMPASS Test
- Thread starter lizab2011
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lizab2011 said:I was taking the test and i wrote all of the questions down and i have know idea which ones i got right and which ones i got wrong so i was wondering if u could help me out...
If the ratio of 10 to Y is 3 to 5 then Y=?
thanks
I'll do another problem for you:
If the ratio of 14 to Y is 8 to 5 then Y=?
\(\displaystyle \frac{14}{Y} \ = \ \frac{8}{5}\)
The lowest common multiple (LCM) of the denominators is 5*Y
Multiply both fractions by the LCM (5 * Y)
\(\displaystyle \frac{14}{Y}\cdot (5 * Y) \ = \ \frac{8}{5}\cdot (5 * Y)\)
Eliminating common factors from numerator and denominator ? from both sides of the equation
\(\displaystyle {14}\cdot (5) \ = \ {8}\cdot (Y)\)
Now isolate 'Y' by dividing both sides by 8
\(\displaystyle \frac{{14}\cdot (5)}{8} \ = \ \frac{{8}\cdot (Y)}{8}\)
\(\displaystyle \frac{70}{8} \ = \ Y\)
\(\displaystyle Y \ = \ \frac{70}{8} \ = \ 8\frac{3}{4}\)
CHECK:
Use the calculated value in the original problem
\(\displaystyle \frac{14}{Y} \ = \ \frac{8}{5}\)
\(\displaystyle \frac{14}{\left (\frac{70}{8}\right )} \ = \ 14 * \frac{8}{70} \ = \ \frac{8}{5}\) ? we have original equation back - so most probably correct
Now follow the exact same procedure for your problem
Some people may complain that this is "too" long - but take short-cuts at your own peril.