Destroyer Qr #64

[queencrown]

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Hey guys! can someone explain this question please??

The weatherman tells you that there is a 70% chance of rain each day for the next 3 days. What is the probability it will rain 2 out of the 3 days?

The answer is 441/1000

HELP!!...thank you 😀

 

[Streetwolf]

Hey guys! can someone explain this question please??

The weatherman tells you that there is a 70% chance of rain each day for the next 3 days. What is the probability it will rain 2 out of the 3 days?

The answer is 441/1000

HELP!!...thank you 😀

(7/10) chance each day for rain, (3/10) for no rain.

You use (3 choose 2) = 3!/2!1! = 3 to choose the 2 days that will rain. It could rain days 1 and 2, days 1 and 3, or days 2 and 3. That's why you need to have that 3 there.

Then you use (7/10)^2 because there are 2 days with rain, and (3/10)^1 because there's 1 day without rain.

3 * (7/10) * (7/10) * (3/10) = 441/1000.