probability

[IrenicMan]

The probability that it will rain in NYC on any given day in July is 30%. what is the probability that it will rain on exactly 3 days from July 5 to July 10 ?

[parallel_chase]

The probability that it will rain in NYC on any given day in July is 30%. what is the probability that it will rain on exactly 3 days from July 5 to July 10 ?

probability that it will rain on any given day = 3/10 or 30%
probability that it will not rain on any given day = 7/10 or 70%

5 july to 10 july = 5,6,7,8,9,10 = 6 days

6C3 = 20

20 * (7/10)^3 * (3/10)^3

OA?

[IrenicMan]

(7/10)^3 * (3/10)^3

kindly explain...

p.s.: I don't hv its correct answer anyway...

[parallel_chase]

(7/10)^3 * (3/10)^3

kindly explain...

p.s.: I don't hv its correct answer anyway...

We have to find the probability that it rains on exactly 3 days

total no. of days = 6

this means 3 days it will rain and 3 days it wont

probability of raining on 3 days = 3/10 * 3/10 * 3/10 = (3/10)^3
probability of not raining on 3 days = 7/10*7/10*7/10 = (7/10)^3

Since we dont know which of the 3 out of 6 days it will actually rain = 6C3

6C3 = 20

probability = 20*(3/10)^3 * (7/10)^3

Hope this helps.

[rafofoa]

parallel chase did you use the binomial distribution type to solve this probability

which is
nCx* Pn-x* (1-P) n-x

[parallel_chase]

parallel chase did you use the binomial distribution type to solve this probability

which is
nCx* Pn-x* (1-P) n-x

Well it was not deliberate, but as it turns out you can also do it with binomial distribution.

[IrenicMan]

Thank you both

[mbaapplicant2008]

It is 20