SOLUTION: A student claims that if a price is now 220% more than it was before, then it is 320% of what it was before, and what it was before is 31.25% of what it is now. Do you agree? Expla

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: A student claims that if a price is now 220% more than it was before, then it is 320% of what it was before, and what it was before is 31.25% of what it is now. Do you agree? Expla      Log On


   

Question 150103: A student claims that if a price is now 220% more than it was before, then it is 320% of what it was before, and what it was before is 31.25% of what it is now. Do you agree? Explain your answer.

Im sorry, but i really don't get this question. =[
Answer by kev82(151) About Me  (Show Source):
You can put this solution on YOUR website!
lets call the new price new_price and the old price old_price. Let's look at the statements one by one
if a price is now 220% more than it was before
Percentages are always over 100, so 220% is 220/100 = 2.2. That's of the old price though, so it is 2.2%2Aold_price more than the old price. So the new price is old_price+%2B+2.2%2Aold_price+=+3.2%2Aold_price 3.2 = 320/100 so the new price is 320% of the old price, yes.
and what it was before is 31.25% of what it is now
What is was before is old_price, and what it is now is new_price. To work out a percentage like this we divide the two things and times by 100. So what we need to do 100%2Aold_price%2Fnew_price. But we know that new_price=3.2%2Aold_price from above, we substitute and get %28100%2Aold_price%29%2F%283.2%2Aold_price%29 There is an old_price on the top and bottom of this division, so it cancels to give 100/3.2 which is 31.25, so again the answer is yes.