Chicken pecking experiment. Animal behaviorists have discovered that the more domestic chickens peck at objects placed in their environment, the healthier the chickens seem to be. White string has been found to be a particularly attractive pecking stimulus. In one experiment, 72 chickens were exposed to a string stimulus. Instead of white string, blue-colored string was used. The number of pecks each chicken took at the blue string over a specified time interval was recorded. Summary statistics for the 72 chickens were y‾= 1.13 pecks, s = 2.21 pecks (Applied Animal Behaviour Science, October 2000).

(a) Estimate the population mean number of pecks made by chickens pecking at blue string using a 99% confidence interval. Interpret the result.

(b) Previous research has shown that μ = 7.5 pecks if chickens are exposed to white string. Based on the results, part a, is there evidence that chickens are more apt to peck at white string than blue string? Explain.