A boat goes 240 miles downstream in the same time it can go 160 miles upstream. The speed of the current is 5 miles per hour. What is the speed of the boat in still water?
Accepted Solution
A:
Answer:25 mph.Step-by-step explanation:Le tx mph be the speed of the boat in still water. Then the speed going downstream is x+5 mph and the speed going upstream is x-5 mph.1. A boat goes 240 miles downstream and it took it [tex]\dfrac{240}{x+5}\ hours.[/tex]2. A boat goes 160 miles upstream and it took it[tex]\dfrac{160}{x-5}\ hours.[/tex]Then[tex]\dfrac{240}{x+5}=\dfrac{160}{x-5},\\ \\240(x-5)=160(x+5),\\ \\3(x-5)=2(x+5),\\ \\3x-15=2x+10,\\ \\3x-2x=10+15,\\ \\x=25\ mph.[/tex]