Answer: I believe the standard deviation will remain the same, 6, choice A.
Step-by-step explanation: Standard deviation is calkculated based on the difference of each point from the mean. If 10 were added to each score, the mean would also increase by 10. That would mean that the difference between the mean and each score would be exactly the same, leading to an identical standard deviation. Sounds crazy, but that's what numbers do for a living.
