The shape of the water is that of a "spherical cap." The formula for the volume of a spherical cap is ...
... V = π·h²·(r -h/3) . . . . . . . from web search
For a radius of 5 in, this is
... V = π·h²·(5 -h/3) . . . . in³
_____
For h=0
... V = π·0²·(5 -0/3) = 0
For h=5 in
... V = π·(5 in)²·((5 -5/3) in) = (2/3)π·5³ in³ . . . . . the volume of a hemisphere of radius 5
keeping in mind that perpendicular lines have negative reciprocal slopes, hmmm what's the slope of the equation above anyway?
![\bf y = \cfrac{2}{3}x\implies y = \stackrel{\stackrel{m}{\downarrow }}{\cfrac{2}{3}}x+0\qquad \impliedby \begin{array}{|c|ll} \cline{1-1} slope-intercept~form\\ \cline{1-1} \\ y=\underset{y-intercept}{\stackrel{slope\qquad }{\stackrel{\downarrow }{m}x+\underset{\uparrow }{b}}} \\\\ \cline{1-1} \end{array} \\\\[-0.35em] ~\dotfill](https://tex.z-dn.net/?f=%5Cbf%20y%20%3D%20%5Ccfrac%7B2%7D%7B3%7Dx%5Cimplies%20y%20%3D%20%5Cstackrel%7B%5Cstackrel%7Bm%7D%7B%5Cdownarrow%20%7D%7D%7B%5Ccfrac%7B2%7D%7B3%7D%7Dx%2B0%5Cqquad%20%5Cimpliedby%20%5Cbegin%7Barray%7D%7B%7Cc%7Cll%7D%20%5Ccline%7B1-1%7D%20slope-intercept~form%5C%5C%20%5Ccline%7B1-1%7D%20%5C%5C%20y%3D%5Cunderset%7By-intercept%7D%7B%5Cstackrel%7Bslope%5Cqquad%20%7D%7B%5Cstackrel%7B%5Cdownarrow%20%7D%7Bm%7Dx%2B%5Cunderset%7B%5Cuparrow%20%7D%7Bb%7D%7D%7D%20%5C%5C%5C%5C%20%5Ccline%7B1-1%7D%20%5Cend%7Barray%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill)

so we're really looking for the equation of a line whose slope is -3/2 and runs through (0,0).

Perimeter = 2 1/8 + 3 1/2 + 2 1/2 = 7 (1 + 4 + 4)/8 = 7 9/8 = 8 1/8
the answer is supposed to be 132 at the most of a
for b it is 165