Turtles, Fields and Distance
The first time the turtles meet, they have travelled a combined length equal to the width of the field. The second time, they have travelled a combined length equal to three times the fields's width. The turtle which had travelled 720 yd at the first meeting has therefore travelled three times that (2160 yd) at the second meeting. As this turtle has then travelled the width of the field plus 400 yd, the field is thus shown to be 1760 yd wide.
Or you can solve it like this:
Let u = speed of the turtle starting from left
and v =
speed of the turtle starting from right and x = width of the field.
From the
given information,
720/u = (x - 720)/v ... ... ( 1 ) and
(x - 720)/u + 11.5 + 400/u = 720/v + 11.5 + (x - 400)/v ... ( 2 )
Solving equations ( 1 ) and ( 2 ), x = 1760 yds.