A boat's crew rowed 20 kilometers​ downstream, with the​ current, in 22 hours. The return trip​ upstream, against the​ current, covered the same​ distance​ but took 55 hours. Find the​ crew's rowing rate in still water and the rate of the current?

1 Answer
Hriman
Apr 8, 2018

#r= 7/11" km/hr"#
#c=3/11 " km/hr"#

Explanation:

Rate= #(km)/(hr)# in this case:

Resultant Rate is what resulted with the rate of the current and their rowing rate, the resultant rates can be calculated with the info given to us:
With current: #(20km)/(22hr)=10/11 " km/hr"#
Against current: #(20km)/(55hr)=4/11 " km/hr"#

System of equations: Let #r# represent rowing rate and #c# the current rate:
With current: #r+c=10/11#
Against current: #r-c=4/11#

Solve by elimination:
#2r= 14/11#
#r= 14/22= 7/11" km/hr"#

Solve for c:
#c= 10/11-r#
#c=10/11-7/11= 3/11 " km/hr"#

Related questions
Impact of this question
628 views around the world
You can reuse this answer
Creative Commons License