Serious Daft Question Time

[DryRob]

The short answer is there may be some commas mixed up with decimal points and the speed is reasonable.

The long answer is:
r = c/(pi*2), c = pi*2*r, s = d/t, t = d/t
r = radius, c= circumference, s = speed, d = distance, t = time

c(earth) = 24901.55 miles @ equator, 24859.82 miles pole to pole ==> average 24880.69 miles
h(orbit) = 240 miles
s = 17239.2 miles per hour

c(orbit) needs calculating:

r(orbit) = r(earth) + h(orbit) ==> c(earth)/(pi*2) + h(orbit)
r(orbit) = 24880.69/(pi*2)  240 ==> 3959.88  240
r(orbit) = 4199.88
c(orbit) = r(orbit)*pi*2 ==> 4199.88*pi*2
c(orbit) = 26388.65 miles

t = d/s ==> t(orbit) = c(orbit)/s
t = 26388.65 / 17239.2 ==> 1.5307 hours
t = 1.5 hours

Due to the earth not being perfectly spherical, variations in the height of orbit and errors in the measured quantities this value can only be considered an approximation.