Lesson Example Discussion Quiz: Class Homework |
Step-1 |
Title: Averages |
Grade: 8-a Lesson: S3-L2 |
Explanation: Let us verify the answer here with the steps. |
Description:
| Step | Type | Explanation | Answer |
|---|---|---|---|
1 |
Problem |
The average of a list of 7 numbers is 23. If we remove one of the numbers, the average of the remaining numbers is 18. What is the number that was removed? |
|
2 |
Hint |
Formula used |
\$"Average" = "sum of set of numbers" / "amount of numbers in set"\$ |
3 |
Step |
The removed number could be obtained from difference between the sum of original 7 numbers and the sum of remaining 6 numbers |
|
4 |
Step |
Removed number |
sum of original 7 numbers - sum of remaining 6 numbers |
5 |
Step |
Using the formula |
\$"Sum of the terms" = "Average" \times "Number of terms"\$ |
6 |
Step |
Sum of original 7 numbers |
\$23 \times 7 = 161\$ |
7 |
Step |
Sum of remaining 6 numbers |
\$18 \times 6 = 108\$ |
8 |
Step |
Using the formula from step 3 |
Removed number = sum of original 7 numbers - sum of remaining 6 numbers ⇒ \$161 - 108 = 53\$ |
9 |
Step |
The number removed is |
53 |
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