In 2013, the average age of a mother at the time of her first childbirth was 25.

Question

In 2013, the average age of a mother at the time of her first childbirth was 25.4. To determine if the average age has increased in 2017, a random sample of 50 mothers is taken and is found to have a sample mean age of 26.5 with a S.D. of four. Test the hypothesis by alpha equals 0.09. What is the critical value in the test? A. 2.2365 B. 2.2380 C. 2.2427 D. 2.2411 E. 1.9253 What is the test statistic in the test? A. 1.9345 B. 1.9545 C. 1.8345 D. 1.9445 E. 1.7345 Compute the upper boundary of the 95% C.I. for the estimated population mean. A. 27.5368 B. 27.8368 C. 27.6368 D. 27.9368

Explanation / Answer

Sample size n=50

Right tailed Critical value tc=t(0.09,50-1)=1.360

This can be checked using following linl

http://www.danielsoper.com/statcalc/calculator.aspx?id=10

Test statistic t=(26.5-25.4)/(4/sqrt(50))=1.9445

Upper boundary=26.5+1.360*4/sqrt(50)=27.2693

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