Crab spiders hiding on flowers. Refer to the Behavioral Ecology (Jan. 2005) experiment on crab spiders’ use of camouflage to hide from predators (e.g., birds) on flowers, presented in Exercise 2.42 (p. 79). Researchers at the French Museum of Natural History collected a sample of 10 adult female crab spiders, each sitting on the yellow central part of LO9 a daisy, and measured the chromatic contrast between each spider and the flower. The data (for which higher values indicate a greater contrast, and, presumably, an easier detection by predators) are shown in the accompanying table. The researchers discovered that a contrast of 70 or greater allows birds to see the spider. Of interest is whether the true mean chromatic contrast of crab spiders on daisies is less than 70.

57 75 116 37 96 61 56 2 43 32 Based on Thery, M., et al. “Specific color sensitivities of prey and predator explain camouflage in different visual systems.” Behavioral Ecology, Vol. 16, No. 1, Jan. 2005 (Table 1).

a. Define the parameter of interest, m.

b. Set up the null and alternative hypotheses of interest.

c. Find x and s for the sample data, and then use these values to compute the test statistic.

d. Give the rejection region for a = .10.

e. State the appropriate conclusion in the words of the problem.