# Further Math Chi^2 Test questionWatch

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Thread starter 1 week ago
#1
Hey! I can't seem to get a handle on this question. The expectation values just crash after the first interval (no matter if I treat them as closed or open intervals).

Not to mention, can't even treat f(x) as a PDF unless 1/40 is actually 1/4 since F(infinity) isn't equal to one otherwise.

However, the answer at the back of the book is a normal test statistic. Please just tell me it's a misprint so that I can move on. Or how to answer it. Really grateful.

Question
https://ibb.co/Ykcb5xB

Answer at the back
https://ibb.co/9bwCNqz
Last edited by BuddyYo; 1 week ago
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1 week ago
#2
(Original post by BuddyYo)
Hey! I can't seem to get a handle on this question. The expectation values just crash after the first interval (no matter if I treat them as closed or open intervals).

Not to mention, can't even treat f(x) as a PDF unless 1/40 is actually 1/4 since F(infinity) isn't equal to one otherwise.

However, the answer at the back of the book is a normal test statistic. Please just tell me it's a misprint so that I can move on. Or how to answer it. Really grateful.

Question
https://ibb.co/Ykcb5xB

Answer at the back
https://ibb.co/9bwCNqz
I guess that its -x/40 in the exponential as that would fit the given data better and its pdf would integrate to unity and the cdf is
(1-exp(-x/40))
which looks about right. However, off out now so maybe have another bash and Ill be back later.
Last edited by mqb2766; 1 week ago
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Thread starter 1 week ago
#3
(Original post by mqb2766)
I guess that its -x/40 in the exponential as that would fit the given data better and its cdf would integrate to unity and the cdf is
(1-exp(-x/40))
which looks about right. However, off out now so maybe have another bash and Ill be back later.
You got it bud. The probabilities and expected values make so much more sense now. Can't believe I didn't figure out the other way I could make it a proper CDF. Not to mention, the intervals are misprinted too. So another potential source of confusion.

In any case. Thanks for the help!
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