Question 1177833
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The other tutor got lost in the middle of her calculations....<br>
The area of the ring of paving stones is half the area of the garden, so the area of the garden plus paving stones is 1.5 times the area of the garden.<br>
Radius of the garden = r
Radius of garden plus paving stones = r+25<br>
{{{(r+25)^2 = (3/2)(r^2)}}}
{{{((r+25)/r)^2 = 3/2}}}
{{{(r+25)/r = sqrt(3/2) = 1.2247}}}
{{{r+25 = 1.2247r}}}
{{{25 = 0.2247r}}}
{{{r = 25/0.2247 = 111}}} with rounding error<br>
ANSWER: the radius of the flower bed is 111cm.<br>
CHECK: (round numbers)
pi(111^2) = 38708
pi(136^2) = 58106
58106/38708 = 1.5<br>