Solving Probability Questions: Mean & CI Estimate

[sinni8]

probability questions please help!

An engineer wishes to estimate the mean setting time of
a new cement mix used in highway spot repairs. From a record of setting times
for 10 spot repairs he obtain
x = 25; 25; 24; 23; 25; 26; 23; 24; 22; 23
minutes, respectively.
(a) Find the mean and standard deviation of the setting time.

(b) Find a 95% confidence interval for the mean setting time if the standard deviation
is known to be ¾ = 1:5 min: Assume a normal distribution
(c) Find a 95% confidence interval for for the mean setting time if the standard
deviation is unknown.

 

[tiny-tim]

Welcome to PF!

An engineer wishes to estimate the mean setting time of
a new cement mix used in highway spot repairs. From a record of setting times
for 10 spot repairs he obtain
x = 25; 25; 24; 23; 25; 26; 23; 24; 22; 23
minutes, respectively.
(a) Find the mean and standard deviation of the setting time.

(b) Find a 95% confidence interval for the mean setting time if the standard deviation
is known to be ¾ = 1:5 min: Assume a normal distribution
(c) Find a 95% confidence interval for for the mean setting time if the standard
deviation is unknown.

Hi sinni8! Welcome to PF!

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