Step 1: Find the mean of the given numbers

GIVEN: 73, 66, 26, 64, 26, 17, 95, 65

Mean = \frac{\text{ Sum of the variables}}{\text{Total number of variables}}

Add up the numbers

73 + 66 + 26 + 64 + 26 + 17 + 95 + 65 = 432

There 8 numbers

Therefore, Mean = \frac{432}{8}

Original mean = 54

Step 2: Find the mean after adding the additional number

73, 66, 26, 64, 26, 17, 95, 65, 36

Add up the numbers

73 + 66 + 26 + 64 + 26 + 17 + 95 + 65 + 36 = 468

There 9 numbers

Therefore, Mean = \frac{468}{9}

Mean = 52

Hence, after adding the additional number the mean is decreased