Question

An ecology class at recently hypothesized that the fronds of sword fern at a local park grow LONGER in the sun than in the shade. To test this hypothesis they randomly sampled 21 sword ferns growing in the shade and 21 sword ferns growing in the sun, and measured the length of the fronds in the upper section of each fern (cm). Welch's df are 37 and α=0.05. Their results are given below:

	x¯	sx	n
Sun	142.8 cm	17.3 cm	21
Shade	125.4 cm	22.2 cm	21

a)What is the value for the point estimate of the difference between the population mean frond length in the sun and the population mean frond length in the shade (sun-shade)?

b) What is the value for the point estimate of the standard error of the difference between the sample mean frond length in the sun and the sample mean frond length in the shade (sun-shade)?

c)Calculate a lower-bound (one-sided) 95%

d) Explain why a lower-bound (one-sided) 95% confidence interval for the difference in population mean frond length between sun and shade (sun-shade) is appropriate for this question

Answer 1