Here is a stemplot for ages at death (in years) of 20 dinosaur specimens, ranging from 2 years up to 28 years.

a. The mean age at death is 15 years and the standard deviation is 7 years. What percentage of the dinosaurs’ ages were within 1 standard deviation of the mean?

b. What percentage of the dinosaurs’ ages were within 2 standard deviations of the mean?

c. The units of standard deviation s are years. What would be the units of variance s²?

d. The shape of the stemplot is fairly normal, with only a bit of left-skewness. Tell how the shape of the distribution for age at death of humans would differ.

e. If paleontologists want to use the mean age, 15 years, to estimate the mean age at death of all dinosaurs, are they mainly concerned with data production, displaying and summarizing data, probability, or statistical inference?

f. Based on the information from this sample, which of these would be the most plausible value for mean age at death of all dinosaurs: 10 years, 14 years, or 18 years?

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