B. In a study of feeding pits of ant lions (an insect that feeds on ants), Austi

Question

B. In a study of feeding pits of ant lions (an insect that feeds on ants), Austin measured the diameter of pits for 150 ant lions. Should he expect these data to be normally distributed or Poisson distributed? 9. Austin found that the mean diameter of pits was 4.8 cm and the standard deviation was 1.2 cm, within what diameter range do approximately 95% of the pit diameters fall? (Hint: you do not need SE to determine this range.) 10, what is the 95% CI of the mean for the mean diameter of pits in Austin's study? (Hint: identify mean, SD, and N from questions 8 and 9, then calculate SE.)

Explanation / Answer

8) Data is expected to be normally distributed

9) mean = 4.8 and std.dev. = 1.2

As per empirical rule, 2-sigma is the range for 95% of the population.

Hence Diameter range = (mean - 2*sigma. mean + 2*sigma) = (4.8 - 2*1.2, 4.8 + 2*1.2) = (2.4, 7.2)

10)

n = 150

SE = std. dev. / sqrt(n) = 1.2/sqrt(150) = 0.098

for 95%, z-value = 1.96

95% CI = (4.8 - 1.96*0.098, 4.8 + 1.96*0.098) = (4.6079, 4.9920)

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