<PRE><B>Question 881687</B>
a man reaches his office from his home 40 minutes too late if he walks at 3 km an hour.
 And 30 minutes too soon, if he walks 4 km an hour.
how far is his office from his home?
:
Let d = distance from his home to his office
the difference between being 40 min late and 30 min to soon, is 70 min
70 min {{{7/6}}} hrs
:
Write time equation; time = dist/speed
Late time - early time = 70 min
{{{d/3}}} - {{{d/4}}} = {{{7/6}}}
multiply equation by 24
24*{{{d/3}}} - 24*{{{d/4}}} = 24*{{{7/6}}}
Cancel the denominators and you have
8d - 6d = 4(7)
2d = 28
d = 28/2
d = 14 km from home to work
:
:
See if that checks out, find the time at each speed
14/3 = 4.67 hrs
14/4 = 3.5 hrs
---------------
time dif: 1.17 hrs which is about 70 min
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