Understanding Energy Usage and Operations

Lesson 14 covers solving problems with rational numbers. It includes analyzing equations to determine which one doesn't belong, calculating water levels in a draining tank, and understanding utility billing with charges and credits. The lesson concludes with a summary of arithmetic rules for rational numbers, emphasizing the importance of order in subtraction and the effects of sign in multiplication and division.

Which equation does not belong because it is the only one with a fraction?

• -100 = -0.001x

• -60t = 30

• x/2 = 5

• x + 90 = -100

What is the change in water level after 5 minutes of draining at a rate of 14 liters per minute?

• -70 liters

• -80 liters

• -50 liters

• -60 liters

How many liters of water were in the tank 3 minutes before the sensor started?

• 798 liters

• 812 liters

• 826 liters

• 840 liters

If the sensor started 15 minutes after draining began, what was the initial water volume?

• 770 liters

• 840 liters

• 980 liters

• 700 liters

What is the charge per kilowatt hour for energy usage by the utility company?

• 10 cents

• 20 cents

• 12 cents

• 15 cents

How many kilowatt hours did the customer use if their charge was $82.04?

• 600 kWh

• 700 kWh

• 684 kWh

• 650 kWh

How many kilowatt hours did the customer generate but not use themselves?

• 180 kWh

• 164 kWh

• 150 kWh

• 200 kWh

What is the result of multiplying two negative numbers?

• Negative

• Undefined

• Zero

• Positive

If you have an odd number of negative numbers in a multiplication, what will the result be?

• Undefined

• Positive

• Negative

• Zero

What is the importance of order when finding the difference between two numbers?

• Order matters only for multiplication

• Order matters for subtraction

• Order matters only for addition

• Order does not matter