The answer is 23.5 ...probably
Hope this will help..........
Answer: 28
Step-by-step explanation:
The mean of 15 numbers = 12
Then , the sum of the numbers = 12x15 = 180
Let the extra number included be
, then
The new sum = 
And the new total number will increase from 15 to 16
new mean = 13 , so we have :





therefore , the extra number is 28
UW is a diameter.
(a). Angle UVX = 23 degrees
(b). Angle UWV = 23 degrees