Posted by Tom 84 on .
Assume that z is the test statistic. (Give your answers correct to two decimal places.)
(d) Calculate the value of z for Ho: ì = 81, ó = 13.3, n = 51, x = 79.7.
1.16 is my answer and it is wrong, can someone tell me how I missed this one, done several and got them right but not this one.

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Kuai,
Yes. your anwser is wrong.

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Tom 84,
In case you think I did not work it and just put a number down I worked it like this 79.781 over 13.3sqrt 51=1.3/1.8623 so did I put the formula in wrong or what, I got all the other ones right with this formula?

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Kuai,
z= (79.7 81)/(13.3/sqrt(51))
z= 1.3/1.862372512
z = 0 .698 or 0.70 
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Tom 84,
Thank you, I am not sure how my calculator came up with that answer. But I had worked it out like you did.

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Kuai,
because you multiply 13.3 sqrt (51) but it is division. 13.3/sqrt(51).