Question

13.9 Damage to grapes from bird predation is a serious problem for grape growers. An article reported on an experiment involving a bird-feeder table, time- lapse video, and artificial foods. Information was collected for two different bird species at both the experimental location and at a natural vineyard setting. Consider the following data on time (sec) spent on a single visit to the location. (Note: Assume the populations are normally distributed.) Species Location x SE mean Blackbirds Expl 40 2.03 Blackbirds Natural 9.8 1.75 Silvereyes Expt! 49.5 4.75 Silvereyes Natural 27 38.1 5.07 (a) Calculate an upper confidence bound for the true average time that blackbirds spend on a single visit at the experimental location. (Use a = 0.05. Round your answer to two decimal places.) 30 33 sec (b) Does it appear that true average time spent by blackbirds at the experimental location exceeds the true average time birds of this type spend at the natural location? Carry out a test of appropriate hypotheses. (Use a = 0.05.) State the relevant hypotheses. (Use wy for blackbirds at the experimental location and uy for blackbirds at the natural location.) 0 Ho: 41 - 4 = 0 H: Ai - Agº 0 O HO: 41 - 42 = 0 H: 41 - 4200 O Ho: 4y - M2 = 0 Ho: 41 - Uzso 0 #g: 4 - 2 = 0 H:44 - uz < 0 Compute the test statistic and P-value. (Round your test statistic to two decimal places and your P-value to three decimal places.) P-value State the conclusion in the problem context. Reject Ho. The data suggests the true average time spent by blackbirds at the experimental location exceeds that of blackbirds at the natural location. Fail to reject Ho. The data suggests the true average time spent by blackbirds at the experimental location exceeds that of blackbirds at the natural location. Fail to reject Ho. The data suggests the true average time spent by blackbirds at the experimental location does not exceed that of blackbirds at the natural location. Reject Ho. The data suggests the true average time spent by blackbirds at the experimental location does not exceed that of blackbirds at the natural location. (c) Estimate the difference between the true average time blackbirds spend at the natural location and true average time that silvereyes spend at the natural location, and do so in a way that conveys information about reliability and precision. (Use a 95% confidence interval for A silvereyes - blackbirds. Use a = 0.05. Round your answers to two decimal places.) sec

Answer 1

(a) 18.01

(b) Option A

t = 1.53

P-value = 0.065

Option C

(c) (17.37, 39.23)

1	2
38.1	9.8	mean
26.34449278	9.585144756	std. dev.
27	30	n
	32	df
	28.3000	difference (1 - 2)
	5.3635	standard error of difference
	17.37	confidence interval 95.% lower
	39.23	confidence interval 95.% upper
	10.9251	margin of error