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A dump of our free Chat sessions, in case it is useful. It excludes white boards used during paid sessions.

tutor3 : Hello Student, May I help you with your Math problems?
student : the height of a certain population of corn plants follow a normal distribution with the mean 145cm and standard deviation 22cm if the sample was increased by 30, what would be the probability that the sampling error between the sample mean and the population mean is less than 10?
tutor3 : Please wait, we are helping other students
student : ok, thank you
student : how long will it take?
tutor3 : asap i will mail you the answer.please wait.thank you
student : no just tell me it here
tutor3 : ok
student : thank you
student : any luck with the anser?
student : answer
tutor3 : no working on that
student : would me giving you the previous question help a bit?
tutor3 : will take some time.why dont u mail it to us and we will send it by your deadline
student : I need by 2maro morning 6am can that happen???
tutor3 : ok wait give me a bit
student : okay thank you!
student : but seriously if i tell you part one of this question would that help?
tutor3 : yes go ahead
student : For a sample of size 16, what would be the probability that the sample mean height is between 135 and 155 cm? answer .9312
tutor3 : ok
student : i dont know if that helps
tutor3 : yes it helps it gives me the sample size which i much needed of
student : okay great!!
tutor3 : give me 10 mins
student : no problem
tutor3 : You want to find the probability of getting a sample mean 135
z1 = (215-220)/4.2426
z2 = (225-220)/4.2426
tutor3 : The standard error of the mean is 30/sqrt(50) = 4.2426
tutor3 : sory i have put in the wrong values
tutor3 : wait
student : okay
tutor3 : The standard error of the mean is 22/sqrt(46) = 3.243.
student : where did u get the 46??
tutor3 : thus You want to find the probability of getting a sample mean 135
z1 = (135-145)/3.243 = -3.083

tutor3 : the initial sample was 16 and this question says increase the size by 30 so size is 46
student : to 30* not by 30
tutor3 : but its written increased by 30 .see the question
student : oh i meant to 30 not by
student : but the question would be solved the same way right
tutor3 : ok then again recalculation..wait
tutor3 : yes the same way only that the obtained z1 value that is here we got z1 = -3.083 , we have see the normal tables for this z-score to get the final answer
tutor3 : is Typing . . . . . . . . . . . . . . . . . . .

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