Answer:
90% is the answer for confidence interval
Step-by-step explanation:
Given that a field test for a new exam was given.75±0.05(75)
i.e. margin of error =0.05(75)=
The population under study was the seniors. Sample mean and std dev were calculated
Stated that the exam creator ased on the results, that on the same exam, 9 out of 10 seniors will have an average score within 5% of 75%
This implies that 9 out of 10 means in percent 90%
Hence the confidence interval is 90%
SInce 5% of 75 is given the range is 75±(75)
Margin of error =3.75
Confidence interval =(75±3.75)
=(71.25,78.75)
We can interpret this we are 90% confident that as sample sizes increase, and samples are drawn at random the average grades of seniors would lie between 71.25 and 78.75
