Question

Please!!

I know I posted this already but there is a typo.

There are 49 mice in a pet shop.
30 mice are white.
27 mice are male.
18 mice have short tails.
8 mice are white and have short tails.
11 mice are male and have short tails.
7 mice are male but neither white nor short-tailed.
5 mice have all three characteristics and
2 have none.

Note:
W represents white mice
M represents male mice
S represents short-failed mice


I made a venn diagram but need help on...
n(M' U S)
The answer says 22+18-7=33
I know that M' means 49-27=22 and the union sign means add the 18 short tails but where does 7 come from? I know you have to subtract the overlap but according to my Venn diagram, the overlap between M and D is 5+6=11.

Answer 1

I was the one that answered you before when you had the typo (you had S instead of A for the short-tailed mice)
and I actually found my scrap piece of paper where I made my Venn diagram.

so....

My Venns agree with your data, and

n(M' union S)
= n(non male) + n(short tailed) - n(non-male AND short-tailed) = 22 +18 - 7 = 33

The 5+6 would be the intersection of male and short-tailed,
but we need to subtract the intersection of the non-males and the shorttailed.
The 11 you are talking about would be the males, not the non-males.
(Put your pinkie finger over the circle containing the males.
that leaves you with the 49, including the 2 outside all 3 circles, notice the 11 you are taling about are already excluded.
Now what do you see as mice belonging to <b>both</b> the 22 remaining mice <b>AND</b> the short-tailed mice not covered by your finger?
Isn't that 7 ?