p. 45 Solutions

 

1.                              P = VI = 110(7) = 770W = 0.770 kW

E = Pt = 0.770 kW(12 h) = 9.24 kWh

C = Er = 9.24 kWh($0.05/kWh) = $0.46

 

2.                              P = VI = 120(15) = 1800 W = 1.8 kW

E = Pt = 1.8 kW(200 h) = 360kWh

C = Er = 360 kWh($0.053/kWh) = $19.08

 

3.                              P = 0.2 kW

E = Pt = 0.2 kW(5 h) = 1 kWh

C = Er = 1 kWh($0.05/kWh) = $0.05

 

4.                              P = 4.5 kW

E = Pt = 4.5 kW(30*2 h) = 270 kWh

C = Er = 270 kWh($0.052/kWh) = $14.04

 

5.                              P = 4.5  kW

E = Pt = 4.5 kW(2 h) = 9  kWh

C = Er = 9kWh($0.0454/kWh) = $0.41

 

6.                              P = 1.2 kW

E = Pt = 1.2 kW(60d * 90/60 h/d) = 108kWh

C = Er = 108 kWh($0.046/kWh) = $4.97

 

7.                              P = 0.145 kW

E = Pt = 0.145 kW(30d * 8 h/d) = 34.8 kWh

C = Er = 34.8 kWh($0.05/kWh) = $1.74

 

8.                              P = 1.5 kW

E = Pt = 1.5 kW(330 h) = 495 kWh

C = Er = 495 kWh($0.05/kWh) = $24.75

 

9.                     B

 

10.                   B

 

11.                   2 and 4