STP226 online Fall18 A 78725 Lauren Kury 1 9/19/1842 Quiz: Ch 8 Quiz: Sampling D
ID: 3071891 • Letter: S
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STP226 online Fall18 A 78725 Lauren Kury 1 9/19/1842 Quiz: Ch 8 Quiz: Sampling Distribution Subr This Question: 1 pt 8 of 10 (5 complete) Y This Quiz: 10 pts Suppose a geyser has a mean time between eruptions of 62 minutes Let the interval of time between the eruptions be normally distributed with standard deviation 18 minutes Complete parts (a) through (e) below (a) What is the probability that a randomly selected time interval between eruptons is longer than 70 minutes? The probability that a randomly selected time interval s longer than 70 minutes is approximately Round to four decimal places as needed) (b) What is the probability that a random sample of 8 time intervals between eruptions has a mean longer than 7D minutes? The probability that the mean of a random sample of 8 time intervals is more than 70 minutes is approximately (Round to four decimal places as needed ) (c) What is the probability that a random sample of 23 time intervals between eruptions has a mean longer than 70 minutes? The probability that the mean of a random sample of 23 time intervals is more than 70 minutes is approximately (Round to four decimal places as needed ) (d) What eflect does increasing the sample size have on the probability? Provide an explanation for this result Fillin the blanks below V as the sample size If the population mean is less than 70 minutes, then the probability that the sample mean of the time between eruptions is greater than 70 minutes (e) What might you conclude it a random sample of 23 time intervals between eruptions has a mean longer than 70 minutes? Select all that apply because the variablity in the sample mean DA The population mean must be more than 62, since the probability is so low B. The population mean may be less than 62 C. The population mean must be less than 62, since the probability is so low D. The population mean is 62 and thes an example of a typical sampling resuit E. The population mean may be greater than 62 F The population mean is 62, and ths s pst a rare sampling Click to select your answer(s). 7-2 O Type here to searchExplanation / Answer
a)for normal disribution z score =(X-mean)/std deviaiton
P(X>70)=P(Z>0.44)=0.3300
b)
for sample size 8; std error =std deviaiton/sqrt(n) =6.364
P(X>70)=P(Z>1.26)=0.1038
c)
P(Xbar>70)=P(Z>2.13)=0.0166
d)
... decreases because the variability in the sample means decrease
e)
option E and F
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