Math Is Fun Forum

tonyz1949

Member

Registered: 2007-08-04

Posts: 20

Math question

1.    Tang-E drink contains 45 percent orange juice by volume. Which of the following expressions represents the percent of orange juice by volume in a mixture of t gallons of Tang-E drink and w gallons of water?

The answer is

      (E)  45t
          --------  %
           (t + w)

Pls show me how to obtain the above answer.

Thanks 

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Math question

This is a product.
45% times t/(t+w).
You can take the product in some instances when it makes sense.
Like t/(t+w) is the fraction of Tang in the Tang-Water.
So 45% of that is ofcourse the percent of orange juice in the Tang-Water solution.
Don't know how to say it clearly, sorry.
Sorry I'm a week late answering.

---

igloo myrtilles fourmis

pi man

Member

Registered: 2006-07-06

Posts: 251

Re: Math question

To get the percentage of orange juice, you divide the volume of orange juice by the total volume.    The total volume is simply the amount of water (w) plus the amount of Tang-E (t).  That's where the (t+w) comes from. 

The orange juice comes only from the Tang-E portion of the mixture.   Specifically, it's 45% of the amount of Tang-E or .45t .    That gives you .45t / (t+w).   Since you want the answer in terms of percentage, you multiply by 100 which gives you 45t / (t+w) %.

tonyz1949

Member

Registered: 2007-08-04

Posts: 20

Re: Math question

Thank you pi man and John E. Franklin for the reply.  It's OK. Better late than never.  I thank you both very much for helping me.  I am preparing for my SAT.