Consider this data set:

{34, 35, 42, 18, 20, 51, 19, 47, 37, 34}

What is the Mean?
What is the Median?
What is the Mode?
What is the Range?

Suppose the value 26 is added to the data set.

What did the Mean decrease by?
What did the Median decrease by?
What is the Mode?
What is the Range?

Mean: (34+35+42+18+20+51+19+47+37+34)/10 = 34.7

Median: In ascending order: 18, 19, 20, 34, 34, 35, 37, 42, 47, 51. Median = (34+35)/2 = 34.5

Mode: No mode as all numbers occur only once.

Range: Highest value - lowest value = 51-18 = 33

After adding 26, the new data set becomes:

{34, 35, 42, 18, 20, 51, 19, 47, 37, 34, 26}

New mean: (34+35+42+18+20+51+19+47+37+34+26)/11 = 32.9

New median: In ascending order: 18, 19, 20, 26, 34, 34, 35, 37, 42, 47, 51. Median = (34+35)/2 = 34.5

Mode: No mode as all numbers occur only once.

New range: Highest value - lowest value = 51-18 = 33

The mean decreased by 1.8 and the median remained the same.