Answer:
B. 1
Explanation:
Let's use the formula for finding the mean of a set of data:
mean = (sum of all data values) / (number of data values)
We know that the mean is 2.2, and we have all the other data values except for one. Let's call the missing value "x". The total number of data values is 10 (since there are 10 scores listed in the frequency table). So we can set up an equation:
2.2 = (sum of all 10 data values, including x) / 10
Multiplying both sides by 10, we get:
22 = sum of all 10 data values, including x
We can then subtract the sum of the known data values from both sides to find the missing value:
22 - (01 + 12 + 23 + 31 + 42 + 51) = x
22 - (0 + 2 + 6 + 3 + 8 + 5) = x
x = 22 - 24 = -2
However, a quiz score cannot be negative, so we made a mistake somewhere. Checking the frequency table, we see that there are no scores of 0 or 1, so the missing score must be 0 or 1. Let's try both possibilities:
If the missing score is 0:
2.2 = (01 + 12 + 23 + 31 + 42 + 51 + 0*1) / 10
2.2 = 18 / 10
2.2 = 1.8
This is not true, so the missing score cannot be 0.
If the missing score is 1:
2.2 = (01 + 12 + 23 + 31 + 42 + 51 + 1*?) / 10
2.2 = (18 + ?) / 10
22 = 18 + ?
? = 4
So the missing score is 1, and the answer is B.