What is the average of all the multiples of 13 from 70 to 144?

Correct option is C

 Given:
Range of multiples of 13 is from 70 to 144
Formula Used:
 First term (a) = smallest multiple of 13 in range
Last term (l) = largest multiple of 13 in range
 Average of multiples = $$\frac{a + l}{2}$$​​
Solution:
Smallest multiple of 13 within the range 70 to 144 is 78.
Largest multiple of 13 within the range 70 to 144 is 143.
​$$\text{Average} = \frac{78 + 143}{2} = \frac{221}{2} = 110.5$$​​
Thus, the average of all multiples of 13 from 70 to 144 is 110.5.