Algebra
posted by Ashley on .
The power in an electric circuit varies inversely with the resistance. If the power is 1200 watts when the resistance is 12 Ohms, find the power when the resistance is 6 Ohms.

A taxi company charges riders a fixed charge of $2.30 plus $1.20 per mile. How many miles must a rider go to have an average cost per mile of $1.30?

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Let n= # miles
2.30 + 1.20n = 1.30n 
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p = k/R
1200 = k/12
k = 14400
so
p = 14400/6
p = 2400 Watts 
c = 1.2 m + 2.3
c/m = 1.2 + 2.3/m = 1.3
2.3/m = 0.1
m = 23 miles 
when P=1200W , R=12Ù
the current is I^2=P/R=100 , I=10A
So the power P=? R=6Ù I=10A
P=I^2R= 100*6=600W