<PRE><B>Question 288985</B>
A uniform-width boardwalk is built around the inside edge of a rectangular parkland that is 10m by 15m. If the boardwalk takes 20% of the lot, how wide is the boardwalk to the nearest centimetre?

The area of parkland = 10* 15 = 150 sq. meters

Boardwalk takes 20% of 150

=20/100 * 150
=30 sq. mtrs.

let the width of the boardwalk be x

the length of parkland excluding width of board walk = 15-2x

width will be 10-2x

150 - (15-2x)(10-2x)=30

150 -{ 150 -30x-20x+4x^2}=30

150-150+50x-4x^2-30=0

4x^2-50x-30=0

taking the roots of the equation 

x1= 50+sqrt(2500+480)  / 8

=50+sqrt2980 /8

=13.07   Or 13

x2 will be negative 

so 13 meters is the width of the board walk



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