math
posted by black mamba on .
what is the area of circle with the diameter of 15 feet, rounded to the nearest whole number?

http://www.aaamath.com/ >>> http://www.aaastudy.com/geo.htm >>> Surface area

recall that the area of a circle is given by:
Area = pi*r^2
since in the problem, diameter is given, we first get radius:
diameter = 2*radius
d/2 = r
15/2 = 7.5 ft = r
thus
A = pi*r^2
A = 3.14*7.5^2
A = ?
now solve this using calculator,,
to round off, first you need to know the place of the digit you want to round off,, in the problem it's 'to the nearest whole number (or the ones digit)'. thus we look at the number to the right of ones digit
if the number to the right of ones digit is:
*greater than or equal to 5, you add 1 to ones digit
*less than 5, the ones digit does not change
for example,,
342.67 >rounding off to nearest whole number gives 343
now apply this to the answer you've got. :)
hope this helps~ :) 
A=d^2*pi/4
A=(15^2)*3.14159/*4
A=225*3.14159/4
A=706.85775/4
A=176.7144375 ft^2
A=177 ft^2
rounded to the nearest whole number