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Venn diagrams probability- can't see why the answer is what it is

http://prntscr.com/hc8qf4

Screenshot of the question above
(edited 6 years ago)
Ummm.. where is the question exactly?
Original post by Radioactivedecay
Ummm.. where is the question exactly?


It didn't upload to TSR properly sorry
Reply 3
click on the link
Original post by Radioactivedecay
Ummm.. where is the question exactly?
the middle section counts towards both the french total & the german total.
Original post by kokaner
click on the link you dip


It was not his fault, I tried uploading the image the first time and it did not work, I had to add the link after I asked the question
Original post by kokaner
click on the link you dip


lol didnt show up for me sorry.
Reply 7
Original post by Radioactivedecay
lol didnt show up for me sorry.


right ho, I apologize
Original post by the bear
the middle section counts towards both the french total & the german total.


How do you calculate the 45 to begin with though- I don't understand how it came from the given numbers
ignoring the outside part which is zero... call the 3 sections a,b,c from left to right.

a + b = 79

b + c = 66

a + b + c = 100

solve these 3 equations & you are done.
Original post by mrwb9876
How do you calculate the 45 to begin with though- I don't understand how it came from the given numbers


You know 100% passed the exam, so that has to be the total of the 3 numbers.

Add the 79 and the 66 together to find out how much the 'overlap' 100 - the answer is 145 ie 45, so put 45 in the overlap area. Then just take 45 from 79 and 45 from 66 to find the numbers in the other parts.
Original post by the bear
ignoring the outside part which is zero... call the 3 sections a,b,c from left to right.

a + b = 79

b + c = 66

a + b + c = 100

solve these 3 equations & you are done.


Thanks!
Original post by threeportdrift
You know 100% passed the exam, so that has to be the total of the 3 numbers.

Add the 79 and the 66 together to find out how much the 'overlap' 100 - the answer is 145 ie 45, so put 45 in the overlap area. Then just take 45 from 79 and 45 from 66 to find the numbers in the other parts.


Thanks

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