Exercise 4.95 discusses weights of male mallards at various stages of development.
a. The "feathered-flightless" stage has mean weight 864 grams and standard deviation 100 grams. Find the proportion of male mallards at this stage that weigh less than 840 grams.
b. The "flying" stage has mean weight 818 grams and standard deviation 91 grams. Find the proportion of male mallards at this stage that weigh more than 840 grams.
Exercise 95
In 1954, researchers Gollop and Marshall defined age classes of ducks based on their plumage, from the earliest stages "bright ball of fluff," and "fading ball of fluff," to the next-to-last stage "feathered-flightless," and, finally, "flying."
a. Suppose male mallards at the "featheredflightless" stage have weights (in grams) with mean 864 and standard deviation 100. Find the z-score of a male mallard at this stage that weighs 840 grams.
b. Suppose male mallards at the "flying" stage have weights (in grams) with mean 818 and standard deviation 91. Find the z-score of a male mallard at this stage that weighs 840 grams.
c. If a male mallard weighs 840 grams, is he more likely to be at the "featheredflightless" stage or the "flying" stage? Explain.