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 manufacturer of television tubes knows from past experience that the average life of a tubeis 2000 hrs. with a s.d. of 200 hrs. A sample of 100 tubes has an average life of 1950 hrs. Test atthe 0.01 level of significance to see if this sample came from a normal population of mean 2000hrs

The quality-control manager at a compact fluorescent light bulb(CFL)factory needs to determine whether the mean life of a large shipment of CFLs is equal to 7450 hours.The population standard deviation is 990 hours.A random sample of 81 light bulbs indicates a sample mean life of 7,252 hours. At the 0.05 level of significance.is there evidence that the mean life is different from 7450 hours? What is the test​ statistic?

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.

Suppose a manufacturer wants to estimate the averagelifespan of a new product they have developed. Theyrandomly select 15 products and test them until they fail.It is known that the average lifespan is 120 hours, with astandard deviation of 10 hours. Assume that the lifespanof the products follows a normal distribution. Themanufacturer wants to know the probability that theaverage lifespan of the product is greater than 130 hours.

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