Answer
$\$0.072/KWh$
Work Step by Step
As we know that
$P=VI$
$\implies P=12\times 15=180W$
Now the energy consumed in 120 minutes is given as
$E=P\times t$
$E=\frac{180\times 120}{60}=0.36KW.hr$
As given that the cost of electrical energy $0.36KW.hr$ is 2.6 cents
Thus for 1 KW.hr the cost is $\frac{2.6}{0.36}=7.22 \space cents=\frac{7.2}{100}=\$0.072/KWh$
