Answer:
The average of the 10 numbers is 195
Step-by-step explanation:
The average of a set of numbers is the sum of the numbers dividing by their number
- Average = The sum ÷ The number
∵ The average of 60 numbers is 55
∴ The average = 55
∴ The number = 60
→ Substitute them in the rule above to find the sum of the numbers
∵ 55 = The sum ÷ 60
→ Multiply each side by 60
∴ 3300 = The sum
∴ The sum of the 60 numbers = 3300
∵ 10 more numbers are included
∵ The average of 70 numbers become 75
∴ The average = 75
∴ The number = 70
→ Substitute them in the rule above to find the sum of the numbers
∵ 75 = The sum ÷ 70
→ Multiply each side by 70
∴ 5250 = The sum
∴ The sum of the 70 numbers = 5250
∵ The sum of the 10 numbers that added is the difference between
the sums of the 60 and 70 numbers
∵ The difference between the sums = 5250 - 3300
∴ The difference between the sums = 1950
→ To find the average of them divide their sum by 10
∵ The average of the 10 numbers = 1950 ÷ 10
∴ The average of the 10 numbers = 195
