Weights of four-year-olds are Normally distributed, with a mean of 40 pounds and a standard deviation of 1.3 pounds. At her four-year checkup, Hannah’s weight measures in the 90th percentile. How much does Hannah weigh?Find the z-table here.

The 90th percentile corresponds to a z-score of about 1.28. Convert that score to a weight using the mean and standard deviation: 40 + (1.28 × 1.3) = 41.664, which rounds to 41.7 pounds. Hannah weighs 41.7 pounds, choice C.

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