Answer:
[a]. sample is 25 randomly selected students
also population is all students
[b]. (20.0, 23.0)
[c]. (8.8, 24.2)
Step-by-step explanation:
here is a step by step process to solving this, i hope you find this helpful.
1). The population is all students who graduated from his school while the
sample is 25 randomly selected students from the email list
2). given alpha = 1-0.86=0.14
critical z value(two tailed) for 86% confidence level is:
z=normsinv(0.07) or normsinv(0.93)=1.476
Margin of error=1.476*(4.6/SQRT(20))=1.5
86% confidence interval for population mean
=21.5+/-1.5
=(20.0, 23.0)
3). if population standard deviation is not known,we will use t distribution.
df=20-1=19
t*=tinv(0.05,19)=2.093
Margin of error=2.093*(5.7/sqrt(20))=2.7
95% confidence interval for population mean
=21.5+/-2.7
=(18.8, 24.2)
cheers i hope this helps!!!!
