Mean=total/the number of values =>total=mean*the number of values
the total of the first set of 8 numbers is : total=8*8=64
the total of the second set of 12 numbers is: 12m
the total of the 20 numbers is: 64+12m
the mean of the 20 number is: (64+12m)/20=5
solve for m: 64+12m=100
12m=36
m=3
The answers to the questions
105.91 is the answer for you
1. 0.54 or 27/50
2. 148.24
3. 0.567735
4. 1.01129
5. 18101.26086