The lifespan of all microwave ovens sold in the United States has a mean of 9 years and a standard deviation of 2.5 years. If a particular microwave oven has z-score of -1.5, how many years did it last? a.) 5.25 years
b.) 7.5

Rachel is studying the population of a particular bird species in a national park. she observes every 10th bird of that species that she can find in the park. her conclusion is that the birds living in the park who belong to that species generally feed on insects. rachel's sample is . based on the sample she picked, rachel's generalization is