Answer:
3.6
Step-by-step 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!