The arithmetic mean of the observations 39, 49, 59, 60, 70, 80, 90, 93 and 90 is:

Correct option is C

Given:

The 9 observations given are: 

$39,49,59,60,70,80,90,93,90$

Concept Used:

$$\text{Mean} = \frac{\text{Sum of all observations}}{\text{Number of observations}}$$ 

Solution:

The observations are: $39,49,59,60,70,80,90,93,90.$

Now, we will find the sum of all the observations:

39 + 49 + 59 + 60 + 70 + 80 + 90 + 93 + 90 = 630

So, the sum of the observations is 630.

There are 9 observations in total.

Now, divide the sum by the number of observations:

$$\text{Mean} = \frac{630}{9} = 70$$ 

​The arithmetic mean of the observations is 70.​