The mean is the average. To find it we add all the data together and divide by the amount of data entries.
[tex] \frac{60+70+80+80+100}{5} =78[/tex]
With 0:
[tex] \frac{0+60+70+80+80+100}{6} =65[/tex]
So adding 0 will decrease the mean. In fact, adding any number that is less than the average will decrease it.
The median is the middle number. First we need to order the data from smallest to largest, then find the middle number.
60, 70, 80, 80, 100
The median is 80.
With 0:
0, 60, 70, 80, 80, 100
The median is in between 70 and 80, so we find the mean of these two number. The result is the median. So with zero, the median is 75.
With zero, both the mean and median decrease. The mean decreased by more, so the answer is the third choice.
