In Scotland in November on average 80% of days are cloudy. Assume that the weather on any one day is independent of the weather on other days.

(i) use normal approximation to find the probability of there being fewer than 25 cloudy days in Scotland in Novermber (30 days).

Question

In Scotland in November on average 80% of days are cloudy. Assume that the weather on any one day is independent of the weather on other days.

(i) use normal approximation to find the probability of there being fewer than 25 cloudy days in Scotland in Novermber (30 days).

anonymous · Answer

I used binomial contribution, which gave an exact answer, but I have to use the normal distribution to get an approximation. Any idea?

amorfide · Answer

best i can help is by giving you this http://www.khanacademy.org/ scroll down to statistics

anonymous · Answer

I know you have to use np and npq, but I have no clue how, and this site doesn't help much... sorry!! :(

amorfide · Answer

this site is very helpful but you can not expect everyone to have been taught the same things as you... we will help when we can but we can't help if we have no knowledge of it... just keep bumping your question until someone answers

amorfide · Answer

until then use khanacademy to learn

anonymous · Answer

what is the answer you got from binomial contribution??

anonymous · Answer

0.572

anonymous · Answer

ummm I give up sorry lol

anonymous · Answer

OK...

anonymous · Answer

but fewer than 25 days is 24 days which is 80 percent of 30 days
so it should be 0.5 if 24 days is a mean
idk I get confused

anonymous · Answer

the end answer should be 0.590

anonymous · Answer

but don't know how to get to that.

anonymous · Answer

hang in there lol

anonymous · Answer

tryin :D