In a recent study of 35 ninth-grade students, the mean number of hours per week

Question

In a recent study of 35 ninth-grade students, the mean number of hours per week that they played video games was 16.6. The standard deviation of the population was 2.8. a. Find the best point estimate of the population mean b. Find the maximum error of the estimate c. Find the 99% confidence interval of the mean time playing video games and interpret. (The price (in dollars) for a particular model of digital camera with 6.0 megapixels and an optical 3X zoom lens are shown below for 10 online retailers. a. Find the best point estimate of the true mean price b. Find the margin of error of the estimate c. Estimate the true mean price for this particular model with 95% confidence and interpret. A researcher wishes to test the claim that the average cost of tuition and fees at a four-year public college is greater than $5700. She selects a random sample of 36 four-year public colleges and finds the mean to be $5950. The population standard deviation is $659. Is there enough evidence to support the claim at alpha = 0.05? (Show clearly the different steps of the test process and draw appropriate conclusion).

Explanation / Answer

5) a) point estimate =16.6

b) for std error of mean =std deviaiton/(n)1/2 =0.473

for 99% CI, z=2.5758

hence maximum error =margin of error =z*std error =1.2191

c)99% confidence interval =sample mean -/+z*std error =15.3809 ; 17.8191

6) only 9 retailer data is available ; please confirm and reply so that can reply on that

7) here null hypothesis: mean =5700

alternate hypothesis: mean>5700

at 0.05 level critical value =1.645

std error of mean =std deviation/(n)1/2 =109.8333

hence test stat z=(X-mean)/std error =(5950-5700)/109.8333=2.276

as test stat z; is in critical region we reject null hypothesis and conclude that tution fee at a 4 year college is greater then 5700

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