Question

1. An average of 32.60 seconds with a standard deviation of 2.50 was calculated from 30 observations in a time study. What is the required total sample size (including the original 30) to be 90% confident that the average is within +-1.5% of the sample mean using this data?    Round up if the calculated number is not an integer.

8. In preparation for a work sampling study, work was started on determining how many observations are required to be 95% confident that the results which are expected to be seen 35% of the time are accurate within +-6% ? Calculate and report the required sample size to meet this requirement.

Answer 1

mean (o) vrage -32.60 Confidence level 1s90 ' 2 Value for conidente ve s .65 Marin of erro r E-±1.5%=±0.015 But uwe know har o.015) he ora Sample S12e n- A5625 2) Snuen considence level 5 a5. margin of error 6% -O-O6 For 9 /. cor fidence level, 곤 value 13 1.96 Mari of erTOr PCI-P) 00 (0-35)0-9a3) 0.O6 n : 242-구6구8 243 rounded o nearesr otege n 'The require Sample 2e η? 24-3.