Question

a ship sails out to an island at the rate of 15 km per hour and sails back to the starting point at 10 km per hour find the average sailing speed for the whole journey

Answer 1

Let total distance between starting and end point be x kmThen time taken to cover it will =Time =distance /speed= x/15 hrs.......... (1)caseIn (2)case Time= x/10 hrsAverage speed =total distance /total time= (x+x) /[(x/15)+(x/10)]=2x/(5x/30)=2x/(x/6)=2x × 6/x= 12 km /hour