Standard deviation / mean problem
In a group of students the mean score for the SAT Math is 510 with a standard deviation of 95. The mean score for the SAT verbal is 490 with a standard deviation of 105.
a) Determine the mean combined score for this group of students.
b) Determine the combined standard deviation for this group of students.
c) What is the probability that one of these students achieves a combined score of 1400 or better?
I dont think you can add means together, obviously not if their standard deviations are different. Just dont know what to do on this one. Any help?