Q: The probability to rain on a given day is 25%. What is the probability that it does not rain during a 2-day period?
A: 8/125, 2/25, 5/16, 9/16 or 3/4
OA is D, 9/16
I can't believe I got this wrong. Here was my method, what did i do wrong?
1 - (prob to rain) = prob NOT to rain
prob. to rain = 1/4*1/4 = 1/16 during 2 day period
1 - (1/16) = 15/16.
How is this incorrect? What step am i missing? Thanks!!
EDIT: Ok I guess They just multiple 3/4 * 3/4 = 9/16 to get the answer.
But why wouldn't it work the other way: 1 - (prob. to occur) = (prob. not to occur)??
Happy New Year!!
Probability problem
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- thankont
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you forgot the fact that it could rain on one day and not on the other and the other way around so you actually have 4 cases
RR. RS, SR, SS so for both days to be sunny we either have 3/4*3/4 =9/16 or 1 - (1/16+3/16+3/16) = 1-7/16 = 9/16
Use the binomial distribution to attack these kinds of problems...
thanx
RR. RS, SR, SS so for both days to be sunny we either have 3/4*3/4 =9/16 or 1 - (1/16+3/16+3/16) = 1-7/16 = 9/16
Use the binomial distribution to attack these kinds of problems...
thanx