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`