# weather probability

• Jan 15th 2010, 10:06 PM
thereddevils
weather probability
A day is either sunny or rainy . The probability that it is sunny for 2 consecutive days is 0.8 . The probability that a rainy day is followed by a sunny day is 0.4 . The probability that the weather forecast expects 1st October to be sunny is 0.75 .

(1)What is the probability that 2nd October is sunny ? What is the probability that 3rd October is also sunny .
• Jan 16th 2010, 03:00 AM
mr fantastic
Quote:

Originally Posted by thereddevils
A day is either sunny or rainy . The probability that it is sunny for 2 consecutive days is 0.8 . The probability that a rainy day is followed by a sunny day is 0.4 . The probability that the weather forecast expects 1st October to be sunny is 0.75 .

(1)What is the probability that 2nd October is sunny ? What is the probability that 3rd October is also sunny .

Draw a tree diagram. If you need more help, please show your work and say where you get stuck.
• Jan 16th 2010, 05:48 PM
thereddevils
Quote:

Originally Posted by mr fantastic
Draw a tree diagram. If you need more help, please show your work and say where you get stuck.

ok ,

I have drawn one but i cant find a way to show it here . However , its sunny or rainy and branch out to sunny or rainy again .

fisrt day(1st october) is sunny , 0.75 , rainy , 0.25

p(two concecutive days sunny)=0.8

p(rain followed by sunny)=0.4

P(2nd october is sunny)=0.8 x+0.4 y=1.2

end up with something funny (Crying)
• Jan 16th 2010, 06:19 PM
mr fantastic
Quote:

Originally Posted by thereddevils
ok ,

I have drawn one but i cant find a way to show it here . However , its sunny or rainy and branch out to sunny or rainy again .

fisrt day(1st october) is sunny , 0.75 , rainy , 0.25

p(two concecutive days sunny)=0.8

p(rain followed by sunny)=0.4

P(2nd october is sunny)=0.8 x+0.4 y=1.2

end up with something funny (Crying)

First question:

0.8 + (0.25)(0.4) = ....