According to the report the standard deviation of montly cel

According to the report, the standard deviation of montly cell phone bills was $48.77 three years ago. A researcher suspects that the standard deviation of monthly cell phone bills is less today.

a) Determine the null and alternative hypotheses. Choose the correct answer below.

a) H0: u = $48.77 ; H1:u>$48.77

b) H0: u = $48.77; H1: u<$48.77

c) H0: o = $48.77; H1: o<$48.77

d) H0: o=$48.77; H1: o does not equal symbol $48.77

B) Expalin what it would mean to type I error. Choose the correct answer below.

a) The same evidence led the researcher to believe the standard deviation of monthly cell phone bills is less than $48.77, when in fact the standard deviation of bills is $48.77

b) The sample evidence led the reseacher to believe the standard deviation of montly cell phone bills is different from $48.77, when in fact the standard deviation of bills is $48.77

c) The sample evidence did not lead the researcher to believe the standard deviaton of montly cell phone bills is less than $48.77, when in fact the standard deviation of bills is less than $48.77

C) Explain what it would mean to take a Type II error. Choose the correct answer below.

a) The sample evidence led the researcher to believe the standard deviation of monthly cell phone bills is less than $48.77, when in fact the standard deviation of bill is less than $48.77

b) The sample evidence did not lead the researcher to believe the standard deviation of montly cell phone bills is different from $48.77, when in fact the standard deviation of bills is different from $48.77.

c) The sample evidence did not lead the researcher to believe the standard deviation of monthly cell phone bijlls is less than $48.77, when in fact the standard deviation of bills is less than $48.77.

Solution

(A) c) H0: o = $48.77; H1: o<$48.77

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(B) type I error: We reject the null hypothesis when it is true.

a) The same evidence led the researcher to believe the standard deviation of monthly cell phone bills is less than $48.77, when in fact the standard deviation of bills is $48.77

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(C)Type II error: We do not reject the null hypothesis when it is false.

c) The sample evidence did not lead the researcher to believe the standard deviation of monthly cell phone bijlls is less than $48.77, when in fact the standard deviation of bills is less than $48.77.