5th grade math (word problems)
posted by Alex .
I'm not sure how to solve this: A group of friends went to an amusement park. 10 of them rode the ferris wheel, 15 rode carousel, and 11 rode the roller coaster. 7 of them rode both the ferris wheel & roller coaster. 4 rode both the ferris wheel & carousel. 5 rode both the carousel and roller coaster. 3 rode all three rides. HOw many friends went to the park?
work:
Ferris wheel & roller coaster 72 = 5
Ferris wheel & carousel 42 = 2
carousel & roller 53 = 2
carousel, ferris wheel, & coaster = 3
5 + 2 +2 +3 = 12 people?

These are best done by using Venn diagrams
(google 'Venn diagram' to get a better idea of that)
Here is a nice short youtube video of a problem that resembles yours, and explains it step by step.
http://www.youtube.com/watch?v=MassxXy8iko
draw the 3 circles within the rectangles and follow the steps outlined in the video
you should get 23 going to the park
let me know if you need further help 
Thanks!!