Step 1: Calculate the total sum of the dataset. The average is given by:
Average = $\frac{\text{Sum of all values}}{\text{Total number of values}}$.
Let A and B represent the smudged values, where A + B = 18 (from Question 20). The eleven known values are:
5, 6, 7, 8, 12, 16, 19, 21, 21, 27, 29.
The sum of the eleven known values:
5 + 6 + 7 + 8 + 12 + 16 + 19 + 21 + 21 + 27 + 29 = 171.
Step 2: Calculate the total sum with A and B. The total sum is:
Total Sum = 171 + A + B = 171 + 18 = 189.
Step 3: Calculate the average.
Average = $\frac{189}{13} = 13$.
Final Answer: 13.
Step 1: Determine the total recalculated sum. The recalculated average is 15. Using the formula for average:
Average = $\frac{\text{Sum of all values}}{\text{Total number of values}}$
15 = $\frac{\text{Recalculated Total Sum}}{13}$
Thus:
Recalculated Total Sum = 15 × 13 = 195.
Step 2: Calculate the correction applied. The original sum of the eleven known values was 171. After adding A and B, the total becomes:
171 + A + B = 171 + 18 = 189.
The recalculated total sum is 195, so the difference due to the correction is:
195 − 189 = 6.
This means one of the recorded values was half of its correct value. Let the wrongly recorded value be x. Then:
$\frac{x}{2}$ + 6 = x = => x = 12.
Step 3: Solve for B. From Question 20, A + B = 18. If A = 6, then:
B = 18 − 6 = 9.
Final Answer: 9.
A | B | C | D | Average |
---|---|---|---|---|
3 | 4 | 4 | ? | 4 |
3 | ? | 5 | ? | 4 |
? | 3 | 3 | ? | 4 |
? | ? | ? | ? | 4.25 |
4 | 4 | 4 | 4.25 |