Answer:
c. 18
Step-by-step explanation:
First, you would find the total sum of the 60 numbers. The average is always the sum of the numbers divided by the number of numbers.
35*18=630
15*10=150
Now we do not know how many numbers the last group has. However, we can find it out doing 60-35-15 to see how many numbers are left. There would be 10 numbers left
10*30=300
630+150+300=1080
1080/60=18
Hence, the answer is C(18)
