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# 3. Dean suspects that statistics teacher increase the grades

3. Dean suspects that statistics teacher increase the grades of the class of 75 students due to his endless love to his beloved students. Dean realized that average grade of previous statistics classes is 64 and she took some of the exams from student affairs departments and note the following grades: 65 75 98 34 76 52 80 84 68. Please help dean to conduct a statistical analysis and (20 points) interpret the results. (20 points)

Thanks, ***** ***** it

Customer: replied 4 months ago.
thanks how long does it take ı have 30 minutes

I will send within that time.

Customer: replied 4 months ago.
okay thanks

mean = (65 +75+ 98+ 34 +76 +52 +80 + 84 +68)/9 = 70.22

standard deviation = 18.67

Null hypothesis H0: µ = 64

Alternate hypothesis H1: µ > 64

t = (x-µ)/(s/√n) = (64-70.22)/(18.67/√9) = -0.999

df =9-1 = 8

critical t-value = 1.860

Rejection region: reject when t > 1.860

since calculated test statistic doesn't fall under the rejection region so we fail to reject the null hypothesis. thus, there is not enough evidence to conclude that grade has increased. 