STUCK!

[smeag]

OK, I can do the number sense test real easy but the place where I struggle is the problems such as:

If P is 20 % of Q and Q is 25% of R, then P is what percent of R?

IF A is 125% of B and B is 120% of C then A is _________% greater than C.

Can someone please please help me with the previous problems?

Also, show me the different formats of the problem and how to do them... Tanks

[michel470]

If P is 20 % of Q and Q is 25% of R, then P is what percent of R?
P=.2Q and Q=.25R...so...substitute! P=.2(.25R) which is .05. I, however, like to think in fractions. 20% is 1/5 and 25% is 1/4, multiply those together and you get 1/20, which is 5%(I suppose this is quicker for me because I was taught to memorize all my fractions, their percents, and decimals when I was younger.)
IF A is 125% of B and B is 120% of C then A is _________% greater than C.
A=1.25B, B=1.2C, or A=(5/4)B, B=(6/5)C so...A=(5/4)(6/5)C which is 6/4(150%) BUT, it asks for percent greater than, meaning you don't include 100%, making it 50%. In like manner, when they ask for percent LESS than, you subtract your answer from 100%.
Ex. P is 30% of Q, Q is 90 10/11% of R, P is what percent less than R?
P=(3/10)Q, Q=(10/11)R, so P is 3/11 of R. Subtract from one(1-(3/11)=8/11) and that's your answer(72 8/11%, actually, but I hope you get the point)