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\magnification 1900

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1.) A pebble dropped into a pond makes a circular wave that travels 
outward at 
a rate 0.4
meters per second. At what rate is the area of the circle increasing 2 
seconds after the pebble strikes the
pond?
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2.) Suppose the distance between two planes must be maintained at 10 
miles.  Suppose plane W is north of a 
radio tower  
and moving south while plane G is east of the same radio tower.  If plane 
G is moving east at 1 mile/second, how 
fast should plane W be moving when plane G is 6 miles from the radio 
tower?


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2.) Suppose car A is 110 miles north of an intersection and traveling 
south at 50 mph.
Suppose car B is 100 miles east of the same intersection and traveling 
west at 20 mph.  
1a.) At what rate are the cars approaching each other after 1 hour?  1b.) 
After 3 hours? 

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3.) A water tank has the shape of an inverted circular cone with base 
radius 12 m and height 4 m. 
Suppose water is leaking out of the cone at a rate of 5 $m^3$/min,  while 
water is being pumped into the cone at a 
rate of 9 $m^3$/min.   Find the rate at which the water level is rising 
when the water is 1.5 m deep.
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