Expert: Richard J. Raridon - 3/22/2008

Question
7.) A motorboat travels 162km in 3 hours going upstream and 882km in 9 hours going downstream. What is the speed of the boat in still water, and what is the speed of the current?

Boat Speed: ___km/h

Current Speed:___km/h



8.) Find two numbers whose sum is 46 and whose difference is 8. We call the two numbers x and y.

x =

y =


Can you please help, my professor states I'm setting up the problem wrong.# 7 I came up with 70 Km and 110 km & # 8 I came up with 6 & 7.

Answer
Your answers for #7 are distances when you want velocities.  
Call the boat speed b and the current c.  
time = distance/speed
3 = 162/(b-c) and 9 = 882/(b+c) so b=76km/h and c=22km/h
8) Well, obviously, 6+7 doesn't equal 46
x+y= 46
x-y= 8
2x = 54, x = 27, y = 19