The life in hours of a 75-watt light bulb is known to be normally distributed with σ = 22 hours. a random sample of 20 bulbs has a mean life of x overscript bar endscripts = 1012 hours. suppose that we wanted the total width of the two-sided confidence interval on mean life to be six hours at 95% confidence. what sample size should be used? round up the answer to the nearest integer.

Someone answer asap for ! max recorded the heights of 500 male humans. he found that the heights were normally distributed around a mean of 177 centimeters. which statements about max’s data must be true? a. the median of max’s data is 250 b. more than half of the data points max recorded were 177 centimeters. c. a data point chosen at random is as likely to be above the mean as it is to be below the mean. d. every height within three standard deviations of the mean is equally likely to be chosen if a data point is selected at random.

Julie buys 2kg of apples and 7kg of pears ? 12.70. the pears cost ? 1.30 per kilogram what is the price per kilogram of the apples? show your working out

If f(x) = 2x + 8 and g(x) = x4, what is (gº)?