Suppose the average SAT-Math score is 643 and the standard deviation of SAT-Math is 105. The average SAT-Verbal score is 480 and the standard deviation of SAT-Verbal is 98. The composite SAT score is determined by adding the Math and Verbal portions.

a. What is the mean and standard deviation of the composite SAT score?

$\displaystyle \mu=$ 

$\displaystyle \sigma=$

b. How much higher, on average, are Math scores vs verbal scores?



c. What is the Standard Deviation of the difference?