A manufacturer knows that their items have a normallydistributed lifespan, with a mean of 5.3 years, and standarddeviation of 1.7 years. If 16 items are picked at random, 2% of thetime their mean life will be less than how many years? Give youranswer to one decimal place.
A political candidate has asked you to conduct a poll todetermine what percentage of people support her.
If the candidate only wants a 10% margin of error at a 98%confidence level, what size of sample is needed?
The political candidate will need to sample___ people.
A political candidate has asked you to conduct a poll todetermine what percentage of people support her.
If the candidate only wants a 10% margin of error at a 98%confidence level, what size of sample is needed?
The political candidate will need to sample___ people.
You measure 38 textbooks' weights, and find they have a meanweight of 32 ounces. Assume the population standard deviation is7.4 ounces. Based on this, construct a 90% confidence interval forthe true population mean textbook weight.
Give your answers as decimals, to two places
I am 90% confident that the mean weight of textbooks is between___and___ ounces.
A researcher studying the lifespan of a certain species ofbacteria. A preliminary sample of 30 bacteria reveals a sample meanof ¯x=76x¯=76 hours with a standard deviation of s=6.8s=6.8 hours.He would like to estimate the mean lifespan for this species ofbacteria to within a margin of error of 0.5 hours at a 99% level ofconfidence.
What sample size should you gather to achieve a 0.5 hour margin oferror?
He would need to sample___ bacteria.
