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# S2 Question? Binomial distribution?

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1. the mean= 3
the variance is 2.25

Find P( mean- variance < X is less than or equal to the mean)

How do you do this please?
2. (Original post by APersonYo)
the mean= 3
the variance is 2.25

Find P( mean- variance < X is less than or equal to the mean)

How do you do this please?
Have you substituted the terms in the inequality to get something that looks like
($P( a \leq X \leq b)$)
where a and b are numbers?
3. (Original post by SeanFM)
Have you substituted the terms in the inequality to get something that looks like
($P( a \leq X \leq b)$)
where a and b are numbers?
Yes. I got
4. (Original post by APersonYo)
Yes. I got
I see someone has edited your post so I'm not 100% sure what you originally said.. that is not your fault, I think someone is trying to help you format it correctly.

But yes, you're right, you need to find
($P( 0.75 < X \leq 3)$)

Do you know how to solve it from there? no worries if you don't. (I dropped a very subtle hint in my earlier post where I've turned it into the form )

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