Confidence Interval Statistics

Question

 Velvetleaf is a particularly annoying weed in cornfields. It produces lots of seeds, and the seeds wait in the soil for years until conditions are right. How many seeds do velvetleaf plants produce? (Use 98% confidence).

Here are counts from 28 plants that came up in a cornfield when no herbicide was used:

2450	2504	2114	1110	2137	8015	1623	1531	2008	1716
721	863	1136	2819	1911	2101	1051	218	1711	164
2228	363	5973	1050	1961	1809	130	880

Answer 1

The 98% confidence interval for population mean is (sample mean)±2.15*(sample standard deviation s)/sqrt(n)

The sample mean is 1868 and the sample standard deviation is 1650. The sqrt(28) is about 5.29. So the confidence interval is

1868 ± 1650*2.15/5.29 = 1868 ± 671 = [1197, 2539]