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**1. Homework Statement**

A street light is at the top of a 18 ft tall pole. A woman 6 ft tall walks away from the pole with a speed of 8 ft/sec along a straight path. How fast is the tip of her shadow moving when she is 30 ft from the base of the pole?

**2. Homework Equations**

http://imageiso.com/out.php/i26481_Relatedrates.JPG [Broken]

18/x = 6(x-y)

**3. The Attempt at a Solution**

y=30 ft

simplified 12x=18y

tip of shadow will be at 45 ft

d/dt 12x = d/dt 18y

dx/dt 12 = dy/dt 18

if i plug the 8ft/s as my dx/dt i get a dy/dt of 16/3ft/s

but that cant be the right answer since i didnt use the 30ft given in my original question

where am i going astray?

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