The average of a set of 6 numbers is 3.5. If the number 4.2 is added to the set, what is the average of the new set of numbers?

3.6

Explanation:

Mean average is calculated by adding all the given numbers together and diving the sum by the number of numbers.

If 6 numbers have a mean of 3.5, it means that the sum of all 6 numbers is 21. (3.5x6).

If we add a 7th number of 4.2, then the total sum of all 7 numbers is now 25.2. (21+4.2=25.2).

25.2/7=3.6

The mean of the new set of 7 numbers is 3.6

(Total of the seven numbers divided by number of numbers)

Hope this helped!