Answer:
The cost of using the hair dryer for 15 minutes is
Explanation:
The parameters given in the question are;
The electric current drawn by the the air dryer, I = 11 A
The voltage to which the hair dryer is connected, V = 120 V
The duration of usage of the hair dryer = 15 minutes = 60 minutes /4 = 1 hour/4 = 0.25 hour
The electrical energy costs $0.09/kW·h
The power consumed by the hair dryer = I × V = 11 × 120 = 1320 Watts = 1.32 kW
The energy used by the hair dryer in 15 minutes (0.25 hour) = 1.32 × 0.25 0.33 kW·h
The energy used by the hair dryer in 15 minutes (0.25 hour) = 0.33 kW·h
The energy cost = $0.09/(kW·h)
Therefore;
The cost of using the hair dryer for 15 minutes (0.25 hour) = 0.33 kW·h/($0.09/(kW·h)) = $33/9 = $3 2/3 = $3.6.