Question

1. You measure 37 backpacks' weights, and find they have a mean weight of 58 ounces. Assume the population standard deviation is 4.3 ounces. Based on this, what is the maximal margin of error associated with a 90% confidence interval for the true population mean backpack weight.

Give your answer as a decimal, to two places ± ounces

2. You are a researcher studying the lifespan of a certain species of bacteria. A preliminary sample of 40 bacteria reveals a sample mean of ¯x=80x¯=80 hours with a standard deviation of s=7s=7 hours. You would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.6 hours at a 99% level of confidence.

What sample size should you gather to achieve a 0.6 hour margin of error? Round your answer up to the nearest whole number.

n =   bacteria

3. An engineer wishes to determine the width of a particular electronic component. If she knows that the standard deviation is 3.1 mm, how many of these components should she consider to be 95% sure of knowing the mean will be within ±0.3±0.3 mm?

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Answer 1