Question

A boat goes 30Km upstream and 44km downstream in 10 hrs. In 3hrs it can go 40km upstream and 55km downstream. Determine the speed of the stream and that of the boat in still water

Answer 1

Step-by-step explanation:

• upstream=x-y
• down stream=x+y
• so, 30/x-y+44/x+y=10
• 30(1/x-y)+44(1/x+y)=10
• let,1/x-y=a,1/x+y=b
• 30a+44b=10......eq1
• 40a+55b=13........eq2
• eq1×4,eq2×3
• 120a+176b=40
• 120a+165b=39
• 11b=1
• b=1/11
• substitute in eq
• therefore x=8
• y=3