SOLUTION: Here's another one I need help with: Every day Andrew wakes up and gets dressed. The probability that he will wear a long-sleeved shirt is 7/10. The probability that he will wea

Question 522680: Here's another one I need help with:
Every day Andrew wakes up and gets dressed. The probability that he will wear a long-sleeved shirt is 7/10. The probability that he will wear a long-sleeved shirt and shorts is 1/10. The probability that he will wear a long-sleeved shirt OR shorts is 9/10. What is the probability that he will wear shorts?
I think it would be 9/10 less 7/10 plus 1/10 equals 3/10, but that doesn't make logical sense. I think the ANSWER should be 1/10, but if that IS right, how would I arrive at it?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Every day Andrew wakes up and gets dressed. The probability that he will wear a long-sleeved shirt is 7/10. The probability that he will wear a long-sleeved shirt and shorts is 1/10. The probability that he will wear a long-sleeved shirt OR shorts is 9/10. What is the probability that he will wear shorts?
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Formula: P(A or B) = P(A) + P(B) - P(A AND B)
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P(L OR s) = P(L) + P(s) - P(L AND s)
9/10 = 7/10 + P(s) - 1/10
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9/10 = 8/10 + P(s)
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P(shorts) = 1/10
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Cheers,
Stan H.
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