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Im confusing the questions with and / or.

table:
Grade level | Bird | Cat | Dog | Fish
6th graders | 9 | 27 | 42 | 3
7th graders | 12 | 36 | 56 | 4
1. what is the probability randomly selected student is an 7th grader and prefers a bird as a pet?
a. 33%
b. 6%
c. 75%
d. 28%
my answer is C, i add all of pets of 7th graders row except bird, (96/108)-(12/108)=77

2. What is the probability randomly selected student is an 7th grader or prefers a bird as a pet?
a. 33%
b. 62%
c. 19%
d. 46%
really struggling with this

2 answers

I counted 189 students
There are 12 7th graders who like birds
to the prob = 12/189 = .063... or 6.3%

For "and" the event must be in both groups
For "or" it is in one OR the other, including both
but make sure you don't count 7th grader AND birdlover twice

so 7th graders ---- 12+36+56+4 = 108
bird lovers -------- 9+12 = 21
total = 108+21 - 12 = 117
prob = 117/189 = .619 or appr 62%
thank u