41) Circumference of a circle is 2*pi*radius, or pi*diameter.
Diameter given is 0.5cm, so circumference is 0.5pi, approximately 1.57cm.
It says scale is 1 cm to 2.5ft. Use dimensional analysis. You can multiply by 2.5ft / 1 cm because it equals 1, and multiplying by 1 doesn't change the value (just the units here).
1.57cm * 2.5ft
-------- = 3.925ft
1 cm
C) 4 feet
42) 6% of $900 is 0.06*$900, which is $54.
$900 is including tax, so subtract the tax ($54) to get the price before tax.
$900 - $54 = $846
A) $846