# Energy - 7th grade (12y) - examples

- Excavation

Mr. Billy calculated that excavation for a water connection dig for 12 days. His friend would take 10 days. Billy worked 3 days alone. Then his friend came to help and started on the other end. On what day since the beginning of excavation they met? - Water

Mix 68 l of water with temperature of 87 °C, 17 l warm of 42 °C and 55 l water of 50 °C. What is the temperature of the mixed water immediately after mixing? - Rates

When gas consumption, the consumer may choose one of two rates: rate A - which pays 0.4 € per 1 m^{3}of gas a flat monthly fee of 3.9 € (regardless of consumption) rate B - which pays 0.359 € per 1 m^{3}of gas a flat monthly fee of 12.5 € From what monthl - Three drivers

Three driversdriving the same direction found that they have same amounth of gasoline. The first is enough to go 6 km, 4 km second and third 3km. Gasoline they divided so all three just drove to the nearest petrol station. How many km away was a petrol sta - Motor physics

Car traveling at 130 km/h on the highway. Pulling power of the motor is 8 kN. Determine engine power in kW. - Cows

20 cows has food for 60 days. We reduce the dose to two-thirds for 18 cows. How many days will be fed? - MPG

252 miles a week fills up twice a week. Each fill is 38 gallons. What is gas mileage of the car? - Fuel mileage

You have 3/8 tank of fuel. Estimate fuel consumption @ 6mpg. Estimate speed @ 50mph. Your fuel tank holds 200 gals. Figure out fuel mileage. - Efficiency

What is the power output of kettle 2 kW with efficiency 90%? - Ounce

749 calories in a 7 - ounce serving . What is the unit rate? - Electric energy

There are 875 identical light bulbs in the sports hall lighting for 2 hours. How long does the same amount of electricity consume 100 such bulbs? - Calories

A large order of McDonald’s french fries has 500 calories. Of this total, 220 calories are from fat. Find the ratio of the calories from fat to total calories in a large order of McDonald’s french fries. - Natural gas in kWh

Gas consumption for 2017 was 11,301 kWh I paid 532 € How much 1 m^{3}? - Gasoline price

At 34.4 cents per liter, how much will 42 liters of gasoline cost? - Calories 2

Ben eats approximately 2400 calories per day. His wife Sarah eats 5/8 as much. How many calories does Sarah eat per day?

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