Question is probability that a student owns a bicycle is 46%, a student owns a car is 73%, and a student owns either a bicycle or car is 91%. Find the probability that a student owns both.
How do I solve this? Can someone show me the steps?
Hey anon, im not in stats but i am in Calc and i think this is kind of a cool question. Im tryna figure it out along with you ill post some of my findings shortly
So i drew it out. Imagine theres 10 people.
50% bikes, 70% Car, 90% either or.
according to the diagram i made i figure 30% of the people must own both.
The question is how do you take 50, 70, and 90% and get the answer 30%? Once we figure that out, you can just do the same thing with your numbers and get your answer.
>>150219
Thanks for the "help." I dont understand it any better but at least now im amused.
i'm in stats, and while i haven't seen that type of question, i've seen a similar type where it gives groups like this:
x percent of people do x thing, y percent of people do y thing, and z percent of people do x and y
and you're asked to find the opposite of your question, to find the percent of people that do either or
anyways you solve the question type i mentioned by doing (x percentage) + (y percentage) - (z percentage), which when applied to your question gets 28%, which seems similar to that calc guy's diagram so it might hold water since it's basically just the opposite of the question i've seen
check your book, in my book this stuff was in the early chapters
>>150223
Basically in math when dealing with probablity or statistics its best to work with a situation where you have 100 of something, that makes the percentages more tangible (I just didn't want to draw 100 circles, just imagine those circles represent 10 people)
So that being said... Imagine you have 100 people. using your stats, 46 of them own a bike, and 73 own a car.
imagine 100% of the people own either a bike or a car. if you add the 73 people to the 46 people, you get 119. That makes no sense, you cant have 119 people out of 100 people, so those 19 extra people must own both a car and a bike.
moving on to your situation... Now theres 91 people who own either a car or a bike. we can disregard those 9 people that own neither (represented by mr poorfag over there) that means that this time there's 119 out of 91. The overlap is now 20 people, so those 20 must own both
20/100= 20%, your probability is 20%
>>150231
**28%
I made a mistake subracting 119-91
it equals 28, not 20
so the guy above me was right, but he used equations, im trying to show you why it works so you dont have to remember equations. maths about intuition, not cramming shit in your head.
>>150232
My teacher wants me to show equations though, personally I prefer using intuition, which led me to ask 4chan for help haha
Thanks for all the replies everyone
>>150236
no problem dude
also in my book it's called the addition rule so you can look that up for more reference
