1.  If X and Y are independent random variables with means μX = 9.5 and μY = 6.8, and standard deviations σX = 0.4and σY = 0.1, find the means and standard deviations of the following:

a.  3X

b.  Y − X

c.   X + 4Y

2.   The bottom of a cylindrical container has an area of 10 cm2 . The container is filled to a height whose mean is 5cm, and whose standard deviation is 0.1 cm. Let V denote the volume of fluid in the container.

a.  Find μV .

b.  Find σV .

3.   The lifetime of a certain transistor in a certain application has mean 900 hours and standard deviation 30 hours. Find the mean and standard deviation of the length of time that four bulbs will last.