Question

Imagine our population of interest is all of the students who took a statsquiz. The average quiz score from all of the students in the class was 85 and the variance was 5. Imagine we could select several different samples from this population of 85 students. What would the standard deviation of the sampling distribution of the mean be for N=5?

A set of phones are normally distributed with a mean of 900 dollars and a standard deviation of 70 dollars. What proportion of phone prices are between 650 dollars and 925 dollars?

If the score variance were 40 and the error variance were 22, then the reliability would be?

Answer 1

1st part :

SDsample = SD/(n^0.5)

= 5/(5^0.5)

= 2.2361

standard deviation of the sampling distribution of the mean for N=5 is 2.2361

2nd part :

P(z<Z) table :

x = price of phone

P(650<=x<=925) ;

P(650<=price of phone<=925) = 0.6393

3rd part :

reliability formula :

R = (Varscore - Varerror)/(Varscore)

= (40-22)/40

= 0.45

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