# Stats question

• Jan 30th 2009, 08:14 AM
mitch_nufc
Stats question
If 85% of people have a bowl of cereal for breakfast, 60% of people have some toast for breakfast, and 50% of people have both cereal and toast for breakfast, what proportion of people have neither cereal nor toast for breakfast?
• Jan 30th 2009, 08:21 AM
redwing
Maybe this equation can help (it's called the inclusion-exclusion principle):

n(R union S) = n(R) + n(s) - n(R intersection S)

Note: drawing venn diagrams helps too a lot of times
• Jan 30th 2009, 08:24 AM
mitch_nufc
The only problem is, I've never done stats in my life :|... I can do pure math, applied math etc very well, but the last time i done stats was about 5 years ago so im sort of learning everything by scratch to be able to tackle these questions
• Jan 30th 2009, 08:26 AM
Greenb
If 50% are having both cereal and toast it means that of the 85% eating cereal only 35% are eating just that.
Same goes for the toast, of the 60% eating toast only 10% are eating just that leaving 55% eating neither.
• Jan 30th 2009, 08:29 AM
mitch_nufc
Thanks for all your replies but I cant see how I can form a formal arguement to do these questions? :( How would the working to the solution of this problem go? :S
• Jan 30th 2009, 08:33 AM
Greenb
When your dealing with these kind of problems the solution is mostly displayed in a venndiagram graphicly.

Venn diagram