First, from the formula given we solve the equation for D:
Now, substituting the given data:
(a) PD=405 cu in, L=4.7 in, and N=7,
in the above equation we get:
(b) PD=399.4 cu in, L=2 in, and N=6,
in the above equation we get:
Answer:
(a) 3.96 in.
(b) 6.51 in.