Question: Hi, I was having problem doing this problem.
Question:
Suppose the temperature during June is normally distributed with the mean= 20 degrees C and standard deviation= 3033 deg. A i the event that temperature is between 21.11 deg C. B is the event that the temperature is over 25Ged C. Event C is the temperature is below freezing point. Find the following probabilities:
A) P(A)
b) P(B)
C) P(C)
D) P(C given B)
E) P(neither A nor B)
F) find the expected number of days in June when event B will occur.

I know how to find questions A-D
I am only having problem with question E and F. Can you please help me. Thank You.

Hi Farina,

P(neither A or B) = 1 - P(A or B) since, for the event "neither A nor B" to occur, Both A and B cannot occur. You can 1 - P(A or ) since

P(A or B) = P(A) + P(B) - P(A and B)

For part F), you know that there are 31 days in June and you know P(B). Here you might think of P(B) as the proportion of the time that the temperature is over 25 deg C. Thus you would expect that this is the proportion of the days in June when the temperature is over 25 degrees C. Hence the expected number of days in June when the temperature is over 25 deg C is

P(B) 31

Penny