Question 896125
A boat going across a lake 8 km wide proceeds 2 km at a certain speed and then completes the trip at a speed of 0.5 km/hr faster.
 By doing this, the boat arrives 10 minutes earlier then if the original speed had been maintained
Find the original speed of the boat.
:
let s = the original speed
then
(s+.5) = the faster speed for last 6 km of the trip
change 10 min to 1/6 hr
:
Find the time it took at the two speed
{{{2/s}}} + {{{6/(s+.5)}}} = {{{(2(s+.5)+6s)/(s(s+.5))}}} = {{{(2s+1+6s)/(s(s+.5))}}} = {{{(8s+1)/(s(s+.5))}}} 
Find s when the difference is 10 min
{{{8/s}}} - {{{(8s+1)/(s(s+.5))}}} = {{{1/6}}}