Question

3.1

power
Every day a certain household uses a 4.4 KW electric stove for 70 minutes, seven 150 W light bulbs for 7
hours each and miscellaneous appliances amounting to 1.8 KW/h. The 4 KW hot water cylinder switches
on for a total of 120 minutes during the day. If electricity cost 50c a KW/h. what is the monthly electricity
bill. (5 marks)
​

Answer 1

The value is
`C = 30729\ c`

Step-by-step explanation:

From the question we are told that

The power rating of the stove is
`P = 4.4 KW = 4.4 *10^(3) \ W`

The duration of its use everyday is
`t_1 = 70 \ minutes = 1.167 \ hours`

The rating of the light bulbs is
`P_2' = 150 W`

The number is
`n = 7`

The power rating of the total bulb is
`P_2 = 7 * 150 = 1050 \ W`

The duration of its use everyday is
`t_2 = 7 hours`

The power rating of miscellaneous appliance
`P_3 = 1.8 \ KW = 1.8 *10^(3) \ W`

The duration of its use everyday is
`t_3 = 1 hour`

The power rating of hot water
`P = 4 KW = 4 *10^(3) \ W`

The duration of its use everyday is
`t_4 = 120 \ minutes = 2 hours`

Generally the total electrical energy used in 1 month is mathematically represented as

`E = P_1 * t_1 * 30 + P_2 * t_2 * 30 + P_3 * t_3 * 30+ P_4 * t_4 * 30`

=>
`E = 4.4*10^(3) * 1.167 * 30 + 1050 * 7 * 30 + 1.8 *1 * 30+ 4*10^(3) * 2 * 30`

=>
`E = 614598 \ W \cdot h`

=>
`E = 614.6 \ K W \cdot h`

Generally the monthly electricity bill is mathematically represented as

`C = 614.6 * 50`

=>
`C = 30729\ c`