The distance from Pier A to Pier B can be determine by using speed formula.
The distance from Pier A to Pier B is [tex]15\:\rm miles[/tex].
Given:
The time to reach from Pier A to Pier B is 2 hour.
The time took in return is [tex]6 \:\rm hour[/tex].
The speed is [tex]2.5\:\rm mph[/tex].
Write the speed formula.
[tex]v=\dfrac{d}{t}[/tex]
Where, [tex]v[/tex] is velocity, [tex]t[/tex] is time and [tex]d[/tex] is distance.
[tex]d=vt[/tex]
When boat go pier A to B with the current of 2.5 mph.
[tex]d=(v+2.5)\times 2\\d=2v + 5[/tex]
Calculate distance return time.
[tex]d = ( v - 2.5)\times 6\\d = (6v - 15)[/tex]
The above equation we can write as,
[tex]2v+5=6v-15\\20=4v\\v=5\:\rm mph[/tex]
Now, the substitute the value of [tex]v[/tex].
[tex]d = 2v + 5\\d = 2(5) + 5\\d = 15\:\rm miles[/tex]
Thus, the distance from Pier A to Pier B is [tex]15\:\rm miles[/tex].
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