A producer of soap dispensers claims its machine dispense liquidwith a standard deviation of 3.1 ounces. A random sample of 20machines found the standard deviation to be 4.6 ounces. Is thereenough evidence, at the α = 0.05 level of significance, to suggestthe standard deviation is not 3.1 ounces?
A manufacturer of 10cm marbles claims the standard deviation ofit’s marble's diameter is less than 0.21cm. A random sample of 12marbles found the standard deviation of the diameter to be 0.14cm.Is there enough evidence, at the α = 0.01 level of significance, toback up the manufacturers claim?
A powerpack is manufactured with a mean lifetime of 4 years anda standard deviation of 0.6 years. What percent of the powerpackswill have a lifetime greater than 4.1 years?
If a company makes LED lights with a mean lifetime of 2000 hoursand a standard deviation of 120 hours. What percent of the lightshave a lifetime between 1840 and 2100 hours?
