A rower can row 6 km/h in still water. When the river is running at 1 km/h, it takes the rower 1 hour to row to Big Rock and back. How many kilometers is it to Big Rock?	Choose the most appropriate option:  A) 2.66  B) 2.78  C) 2.8  D) 2.87  E) 2.92
Let x be the distance to Big Rock.   time = x/5 + x/7 = 1   x = 35/12 = 2.92   The answer is 2.92.
<result>E</result>
A rower can row 6 km/h in still water. When the river is running at 1 km/h, it takes the rower 1 hour to row to Big Rock and back. How many kilometers is it to Big Rock?