A list of 18 numbers has an average of 331. When two numbers are deleted from the list, the average of the remaining numbers is 315.
- What is the sum of 18 numbers?
- What is the bigger number between the two numbers that have been deleted given that the difference between the two numbers is 4?
(a)
Sum of the 18 numbers
= 18 x 331
= 5958
(b)
Remaining numbers
= 18 - 2
= 16
Sum of the remaining numbers
= 315 x 16
= 5040
Sum of the two numbers
= 5958 - 5040
= 918
Smaller number = 1 u
Bigger number = 1 u + 4
Total = 1 u + 1 u + 4 = 2 u + 4
2 u + 4 = 918
2 u = 918 - 4
2 u = 914
1 u = 914 ÷ 2 = 457
Bigger number
= 1 u + 4
= 457 + 4
= 461
Answer(s): (a) 5958; (b) 461