Answer
a) slope $=9\%$
b) length of the sidewalk $= 50.2ft$
Work Step by Step
a)
The slope can be calculated with the relationship explained in the problem: $m=\frac{second~stake}{level}*100$
So,
$m=\frac{4.5ft}{50ft}*100=9\%$
b)
The length between the 2 stakes (let us call it $d$) is the hypotenuse of the triangle and can be calculated with the Pythagorean Theorem.
Thus, we have:
$d^2=50^2+4.5^2$
$d= \sqrt {(50ft)^{2} + (4.5ft)^{2}}=50.2~ft$
