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Help!!
I don’t get why the diagram has 10 on the right to 12 (the mean) 10 is smaller than 12…

And also what does the x represent in p(x<a)
It’s part d btw

And why isn’t it
P(x<_a) minus p(x<-a) ?? They did it other way round whyyy

(edited 10 months ago)

Reply 1

MindMax2000

Universities Forum Helper

Original post by Alevelhelp.1

Help!!
I don’t get why the diagram has 10 on the right to 12 (the mean) 10 is smaller than 12…

And also what does the x represent in p(x<a)
It’s part d btw

And why isn’t it
P(x<_a) minus p(x<-a) ?? They did it other way round whyyy

I don't get why 10 is ont he right to 12 for C either (the diagram is terrible), but that's not the question you're looking at.

For D:
x represents the rnadom variable, which means a represents a limit by which the random variable can be at. P(x<a) means the chance of x being any value less than a.

The question is asking for the lower limit a in P(a<x<14). I could easily rewrite this as P(14>x>a) and mean the same thing.
This is the same as P(14>x) - P(a>x). You need to write P(a>x) the way it does because you need to know what is the probability below the limit of a, so you can deduct it from P(14>x).
P(x>a) means the probability to the left of a, not right (which is what you need).