The answer is 1.706361672
rearranging the equation you get
32 x D x Q = 0.096167 x PI(D^4-d^4) x sqrt((Ym x SF)^2 - (P^2/ A^2))
then substituting the numbers
4932960 = 0.096167 x PI(625- 363.0254) x sqrt(13167562500-87433.4784)
4932960 = 25.19331136 x PI x 114749.619
42.9889009 = 25.19331136 x PI
therefore PI = 1.706361672
=1.71 correct to 2 dec pl
