Reference no: EM1318207

Q1) "Wheat" pennies are pennies which are minted before 1954.  Following data represent weight (in grams) of random sample of 15 wheat pennies.

 

3.01	3.06	3.13	3.00	3.05
3.07	3.02	2.98	3.04	3.02
3.06	3.03	3.07	3.04	2.96

 

i) What is the point estimate?

 

ii) What is the standard deviation?

 

iii) Construct a 90% confidence interval for the mean weight of a "wheat" penny.

 

iv) What could be done to increase the accuracy of the interval without changing the level of significance?

 

v) Find the t-value such that the area in the right tail is .10 with 25 degrees of freedom

 

vi)  Find the t-value such that the area in the right tail is 0.05 with 30 degrees of freedom.

 

vii) Find the t-value such that the area left of the t-value is 0.01 with 18 degrees of freedom

 

viii) Find the critical t-value that corresponds to 90% confidence. Assume 90 degrees of freedom.

 

ix) What are 4 properties of the t-distribution?