A set of 19 scores has a mean of 6.3. A new score of 8 is then included in the data set. What is th

A set of 19 scores has a mean of 6.3. A new score of 8 is then included in the data set. What is the new mean?

We know the mean formula is:
Sum of scores / Number of Scores = Mean

We're given mean = 6.3 and number of scores = 19, so we have:
Sum of scores / 19 = 6.3

Cross multiply:
Sum of scores = 19 * 6.3
Sum of scores = 119.7

Now a new score is added of 8, so we have:
Sum of scores = 119.7 + 8 = 127.7
Number of scores = 19 + 1 = 20

So our new mean is:
Mean = Sum of scores / Number of Scores
Mean = 127.7/20
Mean = 6.385