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Scienceboy1776
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Homework Statement
A survey concludes that it in average rains 15 of 30 days in may.
Thusly P(R|M) = 1/2
Where M is May and R is rain.
The Weatherservice forcasts fits 2/3 of the time. Thus it does not rain 2/3 of the time.
I bring umbrella with me every day the promise and 1/3 of the days where do not perdict rain.
1) What is the prob that that Weather Service promises dry weather in a day in May?
2) What is the prob that it rains on a day where I did not bring my umbrella?
Homework Equations
P(A|B) = P(A n B)/P(B)
The Attempt at a Solution
By using the formula in condition prob.
I get 1)
P(R|M) = 1/2 P(R) = P(R) = 1 - P(does not rain) = 1 - 1/3 = 2/3
Thus 1/2 = P(R n M) / P(R) -> 1/2 = (R n M)/ (2/3) = 1/3
I am not sure about 2 ?
2) P = 1/3 * 2/3 = 2/9 ?
Hope there is someone who would take a look at it?