<PRE><B>Question 1137749</B>
let d be the diameter, then
:
hp = k * rpm * d^3, where k is the constant of proportionality 
:
We are given that
:
40 = k * 120 * 4^3
:
k = 40/(120 * 64) = 1/192
:
65 = (1/192) * 140 * d^3
:
multiply both sides of = by 192
:
12480 = 140 * d^3
:
d^3 = 12480/140 = 89.1429
:
d = 89.1429^(1/3) = 4.4671
:
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The diameter is 4.47 inches
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:
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