Inference and Sampling Distributions 

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Practice Problems You'll need a pencil and paper for these. You can check your answers with the key offered at the bottom of the page.
2. Suppose that 29% of all highschool seniors are regular smokers. (This is approximately true, according to a 2004 Gallup poll.) If you were take a random sample of 100 high school seniors, what would be the approximate distribution of the sample proportion of regular smokers among them?
3. Suppose that the heights of threemonthold red oak saplings in a greenhouse have a mean of 2.1 inches and a standard deviation of 1.9 inches. You plan to randomly sample 45 of these saplings and average their heights together to get xbar. What is the probability that the mean of the sample heights will be less than 1.7 inches?
4. Again given the supposition that the heights of
threemonthold red oak saplings in a greenhouse have a mean of 2.1
inches and a standard deviation of 1.9 inches, can you calculate the
probability that one
