Problem 1
Answer: 7/10
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Step-by-step explanation:
The formula we'll use is
P(A or B) = P(A) + P(B)
which only works if A and B are mutually exclusive events.
P(A or B) = P(A) + P(B)
P(A or B) = 7/20 + 7/20
P(A or B) = (7+7)/20
P(A or B) = 14/20
P(A or B) = (7*2)/(10*2)
P(A or B) = 7/10
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Problem 2
Answer: 3/4
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Step-by-step explanation:
We'll use the same formula as the previous problem.
P(A or B) = P(A) + P(B)
P(A or B) = 3/10 + 9/20
P(A or B) = 6/20 + 9/20
P(A or B) = (6+9)/20
P(A or B) = 15/20
P(A or B) = (3*5)/(4*5)
P(A or B) = 3/4
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Problem 3
Answer: 3/5
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Step-by-step explanation:
We'll use the same formula as the previous problem.
P(A or B) = P(A) + P(B)
P(A or B) = 7/20 + 1/4
P(A or B) = 7/20 + 5/20
P(A or B) = (7+5)/20
P(A or B) = 12/20
P(A or B) = (4*3)/(4*5)
P(A or B) = 3/5
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Problem 4
Answer: 0
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Step-by-step explanation:
This time we're asked to find P(A and B), but since the two events are mutually exclusive, this means the probability of both occurring is 0.
Mutually exclusive events cannot happen simultaneously.
An example would be flipping heads and tails at the same time on the same coin.
The info about P(A) and P(B) is not relevant.