(Sec. 12.1) Suppose that the expected cost (yy dollars) of a production run is related to the size of the run (xx units) by the equation y=4000+10xy=4000+10x. Let YY denote an observation on the cost of a run. Also, suppose size and cost are related according to a simple linear regression model. a) What is the expected cost when the size of the run is 150 units? b) By how much do you expect the cost to increase if the size of the run is increased by 10 units? c) Suppose that the standard deviation of the random error ϵϵ is $250. What is the probability that the cost of a production run of 150 units will cost more than $6000? d) Suppose the cost is recorded from a production run of 200 units, and then is also recorded from a different production run of 250 units. What is the probability that the cost of the second production run exceeds the cost of the first by more than $1500?