It is required to find√15
The number 15 is between 9 and 16
So, Beau found 3^2 = 9 and 4^2 = 16
So, √15 will between 3 and 4
He thinks a good estimate for √15 = (3+4)/2 = 3.5
Beau's estimate is low correct because 15 is near to 16 more than 9
So, 3.8 or 3.9 would be a good answer for √15 because 3.5 is too low.
