SOLUTION: A boat travels at the speed of 20 Miles per hour in still water. It travels 48 miles up stream, and then returns to the starting point in a total of five hours. The speed of the cu
Question 17943: A boat travels at the speed of 20 Miles per hour in still water. It travels 48 miles up stream, and then returns to the starting point in a total of five hours. The speed of the current is ____ miles per hour.
You can put this solution on YOUR website! A boat travels at the speed of 20 Miles per hour in still water. It travels 48 miles up stream, and then returns to the starting point in a total of five hours. The speed of the current is ____ miles per hour.
distance =speed * time..or...time=distance/speed
Still water speed of boat =20 mph
let the stream velocity be =x mph
so its speed upstream =20-x
its speed down stream =20+x
distance travelled either way =48 miles
time taken to travel upstream=48/(20-x)
time taken to travel down stream =48/(20+x)
total time of travel =5 hours..hence
[48/(20-x)]+[48/(20+x)]=5
48[(20+x+20-x)/((20-x)(20+x))]=5
48*40=5(20^2-x^2)=2000-5x^2
5x^2=2000-1920=8=
x^2=80/5=16
x=4 mph
