Question

A particular electric utility charges customers different rates depending on their daily rate of energy consumption: $0.05/kWh up to 20 kWh, and $0.10/kWh for all energy usage above 20 kWh in any 24-hour period. (a) Calculate how many 100 W light bulbs can be run continuously for less than $10 per week. (b) Calculate the daily energy cost if 2000 kW of power is used continuously.

Answer 1

Answer:

(a) the number of 100W light bulbs is 11

(b) the daily cost of 2000 kW is $4,800

Step-by-step explanation:

charge of energy consumption up to 20 kWh = $0.05/kWh

charge of energy consumption above 20 kWh = $0.10/kWh

(a) number of 100 W light bulbs that can be run continuously for less than $10 per week

Total energy consumed by 100 W in 1 week = (0.1 kW) x (7 x 24 h)

                                                                          = 16.8 kWh

Charge associated with this consumption = $0.05/kWh

let the number of 100 W light bulbs = n

$n(\frac{\ 0.05}{kWh} \times 16.8 kWh) = \ 10\\\\n(0.84) = 10\\\\n = \frac{10}{0.84} \\\\n = 11.9$

Since 0.9 is not a whole number, the number of 100 W light bulbs is 11.

(b) if 2000 kW is used continuously

total energy consumption = 2000 kW x 24 h = 48,000 kWh

The daily cost is calculated as;

$= \frac{\ 0.10 }{kWh} \ \times \ 48,000 kWh\\\\= \ 4,800$