<PRE><B>Question 115828</B>
30=3.14d^2*42/924
30=131.88d^2/924 now cross multiply
30*924=131.88d^2 
27,720=131.88d^2 now divide both sides by 131.88
d^2=27,720/131.88
d^2=210.191
d=sqrt210.191
d=14.5 in. is the diameter.
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50=3.14d^2*60/924
50=188.4d^2/924
188.4d^2=50*924
188.4d^2=46,200
d^2=46,200/188.4
d^2=245.22
d=sqrt245.22
d=15.66 in. is the diameter.</PRE>