A purchasing manager at a university is investigating which brand of LCD projector to purchase for equipping classrooms. Of major concern to her is the lifetime of the light bulbs used in the projectors. One company has published the following frequency distribution from a test of the lifetimes (in hours) of 45 bulbs used in its LCD projectors.Bulb lifetime(in hours) Frequency700 to 749 4750 to 799 8800 to 849 14850 to 899 10900 to 949 5950 to 999 4Based on the frequency distribution, using the midpoint of each data class, estimate the mean lifetime for the light bulbs in the company's test. For your intermediate computations, use four or more decimal places, and round your answer to one decimal place.hours

A factory produces a type of light tube, Its lifespan can be expressed this way: X~(u, 200^2). From experience, it's known that the average lifespan u is 1500 hours. Now, after adopting a new technique, 25 light tubes are randomly selected from those produced and the average lifespan is found to be 1675 hours. With the new technique adopted, what is the value of the test statistic?

The lifetime t (in weeks) of a light bulb can be defined by the force of mortality 0.25t2 +0.4t.A hotel has five hundred rooms, and has just opened with four new light bulbs in eachroom. Light bulbs are checked exactly once a week and all defective bulbs are replacedimmediately.(a) Calculate the number of bulbs that the hotel would expect to replace at the end ofeach of the first, second, and third week of opening

The lifespan of a particular brand of CFL light bulb is uniformly distributed between 19 and 39 months. Assume lifespans are independent from light bulb to light bulb. In a package that contains two of these CFL light bulbs, find the probability that the first bulb lasts for more than 28.3 months or the second bulb lasts for less than 28.2 months.

Below are the lifetimes, in hours, of fifty 40-watt, 110-watt internally frosted incandescentlamps, taken from forced life tests:919 1196 785 1126 936 9181156 920 948 1067 1092 11621170 929 950 905 972 10351045 855 1195 1195 1340 1122938 970 1237 956 1102 1157978 832 1009 1157 1151 1009765 958 902 1022 1333 8111217 1085 896 958 1311 1037702 923Construct :a) Skeletal box plot

Suppose that the lifetimes of old-fashioned TV tubes are normally distributed with a standard deviation of 1.2 years. Suppose also that exactly 35% of the TV tubes die before 4.5 years. Find the mean lifetime of TV tubes. Carry your intermediate computations to at least four decimal places. Round your answer to at least one decimal place.