Answer:
fluid force = 1309 lb
Step-by-step explanation:
Given data 
wide = 63 inches
distance below water surface = 1.5 inches
distance below surface = 40.5 inches
weight-density of seawater W = 64 lb/ft
to find out
fluid force against the window
solution
we consider here A(y) is the depth of fluid and B(y) length of portion at y 
so we can say y1 = 0 so y2 will be 33.5 - 0.5 = 33 inches = 2.75 feet
so A(y) = 33.5/12 - y ) feet
and B(y) = 63 inches = 5.25 feet
fluid force = W 
 A(y) B(y) dy
 A(y) B(y) dy
so take limit y = 0 to y = 2.77
fluid force = 64 
 ((33.5/12) -y ) (5.25) dy
 ((33.5/12) -y ) (5.25) dy
fluid force = 64×5.25/12 
 ((33.5 -12y ) dy
 ((33.5 -12y ) dy
fluid force = 28 

fluid force = 28 × 46.75 - 0
so fluid force = 1309 lb