The circular face of a watch has an area that measures between 800 and 900 square millimeters. what could be the radius of the watch face? use 3.14 for .

Answer
the radius of the face would lie between 15.96 mm and   16.93 mm. 


explanation
the area of a circle is given by;
area =  πr²

where area = 800,
  πr² = 800
r² = 800/3.14
    =254.777
r =  √254.777
    = 15.96 mm

when area = 900
πr² = 900
r² = 900/3.14
    = 286.624
r =  √  286.624
  = 16.93 mm

the radius of the face would lie between 15.96 mm and  16.93 mm. 

A= pi * r^2
800 = 3.14 * r^2
800/3.14 = r^2
255 = r^2
sqrt 255 = r
15.9 rounds to 16mm = r

check..
a = 3.14 * 16^2
a = 3.14 * 256
a = 803. in between 800 and 900

so ur answer, i believe, is 16mm because 17mm would be too much and 15mm wouldn't be enough