Proportion question?

Question

My homework problem:

For every girl taking classes at the martial arts school, there are 3 boys who are taking classes at the school. If there are 236 students taking classes, write and solve a proportion to show the number of boys taking classes at the school.  

 

I can solve this using percentages (25% and 75%), but don't know how to do it using a proportion.

Answer 1

You are on the right track; you just need to think of the percentages as fractions instead. For every girl, there are three boys. This means that there are sets of 4 students (1 of the 4 is a girl, 3 of the 4 are boys, or ¹/₄ and ³/₄).

 

 3           x

---   *   -----

 4         236

 

Cross multiplying time!

 

3 * 236  = 4x

708 = 4x

177 = x

There are 177 boys in the martial arts school.