After a 20% increase, the new price of a radio is $78.00. What was the original price of the radio?

a) $15.60
b) $60.00
c) $62.40
d) $65.00
e) $97.50

Question

After a 20% increase, the new price of a radio is $78.00. What was the original price of the radio?

a) $15.60
b) $60.00
c) $62.40
d) $65.00
e) $97.50

anonymous · Answer

c. 62.4

anonymous · Answer

adila ..please do not just give answers

psymon · Answer

If the radio is $78.00 after a 20% increase, then this means that $78.00 is 120% of some number. So if you can figure out that calculation, you're golden.

anonymous · Answer

The easiest way to do this is by trial and error ..psymon was completely correct a way you can check is take each answer and multiply by 1.2 ...if one is 78 that will be right

anonymous · Answer

ok, great. Let me try to solve it. :) @Psymon

psymon · Answer

Yeah, sure, try to solve it and lets see what you get ^_^

psymon · Answer

And trial and error is not needed : )

anonymous · Answer

well its a pretty simple way :P

psymon · Answer

If you think you got down the method of solving it real well then awesome. Otherwise I can show you how I do it :3

anonymous · Answer

I got 62.4 but I don't think I did it right. :/

psymon · Answer

Yeah, it shouldnt bethat.

anonymous · Answer

isnt it 65?

psymon · Answer

So I have a unique way of thinking of it. I do what I would say is a verbal proportion, meaning I put down the numbers based on how I read the sentence. So this is how I set it up:

|dw:1378192154570:dw|

So let's phrase our question. "78 is 120% of what number?" This is essentially what we're solving. So as I read this "78 is", well, that would be the number I put under "is" in my proportion. Of course 120 fills in the percent category. And "of what number" means I do not know what to put in the of part of my proportion. The 100 on the bottom right always stays there. So that being said, I can plug in all of my numbers and then solve for x by cross-multiplying like so:

|dw:1378192263946:dw|