Answer:
Step-by-step explanation:
Given that data from students doing a lab exercise are as follows:
33,190 31,860 32,590 26,520 33,280 32,320 33,020 32,030 30,460 32,700 23,040 30,930 32,720 33,650 32,340 24,050 30,170 31,300 28,730 31,920
Mean = 30841
Since normal and also sigma is known, std error
=![\frac{\sigma}{\sqrt{n} } \\=\frac{3000}{\sqrt{40} } \\=474.34](https://tex.z-dn.net/?f=%5Cfrac%7B%5Csigma%7D%7B%5Csqrt%7Bn%7D%20%7D%20%5C%5C%3D%5Cfrac%7B3000%7D%7B%5Csqrt%7B40%7D%20%7D%20%5C%5C%3D474.34)
For95% margin of error = ±1.96(474.34) =±929.71
Hence 95% conf interval = 30841±929.71
=(29911.29, 31770.71)