Percent fraction problem?

in a music class of 30 students, 50% study woodwinds, 40% study strings, and 30% study both woodwind and strings. What percent of the students in the class do not study either woodwind or string instruments.





A 25%


B 40%


C 50%


D 60%


E 75%





this is in the sat book, please tell me how you did it

Percent fraction problem?
So there are 50 - 30% = 20% for just woodwinds,


40 - 30% = 10% for just strings.


30% for both.





Add up these three and subtract from 100%. = 40%





B
Reply:50% + 40% - 30%


60%


100 -60 = 40%





B





Why? You add 50% who play woodwinds to 40% who study strings, but you have to subtract 30% who study both, otherwise you're counting them twice. This gives you 60%. This is the number of people who study woodwind or string (or both) instruments. Subtract from 100% to get 40, the percent that study neither
Reply:30*.50 = 15 study woodwinds


30*.40 = 12 study strings


30*.30 = 9 study both





You are looking for the maximum % so you can take:





15(all woodwinds)-9(study both) = 6+12(remaining strings)=18





18/30 = 60% study something





100-60=40% is your answer.

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