I can help you out with the 1st question.
1. The average of 11 numbers is 10. When one number is eliminated, the average of the remaining numbers is 9.3. What is the eliminated number?
*How do you get 9.3?
9.3 is the average after eliminating one value from a set of 11 numbers. (Consider this as given information which will aid us in finding the eliminated number. We need not worry how 9.3 was achieved)
Average Formula -
Avg = (Sum)/total
Average of 11 numbers is 10 (given)
10 = (Sum)/11
Sum = 110
Total Sum of 11 numbers is 110
Now, the question states that when one number is eliminated the average becomes 9.3
Let the eliminated number be say "x"
Avg = (Sum)/total
9.3 = (110-x)/10
93 = 110-x
x = 17
17 is the eliminated number
Cross check -
For 10 numbersSum of 10 numbers = 93
Avg = (sum)/total
Avg = 93/10 = 9.3 (matches the condition given in problem stm.)
For 11 numbers11th number is 17
Sum of 11 numbers = 93 + 11th number (i.e 17) = 93 + 17 = 110
Avg = Sum/total
Avg = 110/11
Avg = 10 (matches the condition given in problem stm.)