# Need urgent help with Related Rates

• Jul 22nd 2009, 07:41 AM
wdma
Need urgent help with Related Rates
Could anyone help me by solving this step by step so I can see what you did there?
Thank you so much in advance. (Wink)

http://10proxy.info/rr.png
• Jul 22nd 2009, 09:03 AM
Calculus26
R = 110q - q^2/200

dq/dt = 55 the rate production is increasing and q = 400

Now we differentiate with respect to time -- note d(q^2)/dt = 2q dq/dt

dR/dt = 110dq/dt -q/100 dq/dt

dR/dt = 110(55)-(400/100)(55)

dR/dt = 6050 - 220 = 5830dollars/day
• Jul 22nd 2009, 09:19 AM
wdma
Quote:

Originally Posted by Calculus26
R = 110q - q^2/200

dq/dt = 55 the rate production is increasing and q = 400

Now we differentiate with respect to time -- note d(q^2)/dt = 2q dq/dt

dR/dt = 110dq/dt -q/100 dq/dt

dR/dt = 110(55)-(400/100)(55)

dR/dt = 6050 - 220 = 5830dollars/day

Thank you so much Calculus26. I'm just uncertain about the last answer, a friend of mine told it can't be \$5830. He said that I might wanna try plugging in the derivative, but I 'm not sure what I'm getting wrong here.
Any ideas?
• Jul 22nd 2009, 09:35 AM
Calculus26