Total change in grade:
$A = g_2 - g_1 = 1 + 5$
$A = 6\%$
Rate of change in grade
$\Delta g = \dfrac{0.4}{20} = 0.02\% ~ \text{per meter}$
Length of Parabolic Sag Curve
$L = \dfrac{A}{\Delta g} = \dfrac{6}{0.02}$
$L = 300 ~ \text{m}$ ← Answer: [ C ]
On CASIO Calculator: f(x)-991ES PLUS
MODE → 3:STAT → 2:A+BX
AC
$L = 1\hat{x} = 300 ~ \text{ft}$ ← Answer: [ C ]
Note:
$\hat{x}$ = SHIFT → 1:[STAT] → 5:Reg → 4:x-carret
