Answer:
Step-by-step explanation:
Sure, here are five examples of problem-solving using the GRESA method for speed:
Example 1:
Given: A car travels 240 km in 4 hours.
Required: What is the average speed of the car?
Equation: Speed = Distance / Time
Solution: Speed = 240 km / 4 hours = 60 km/hour
Answer: The average speed of the car is 60 km/hour.
Example 2:
Given: A train travels at a speed of 100 km/hour for 2 hours, and then at a speed of 80 km/hour for the next 3 hours.
Required: What is the total distance traveled by the train?
Equation: Distance = Speed x Time
Solution: Distance = (100 km/hour x 2 hours) + (80 km/hour x 3 hours) = 200 km + 240 km = 440 km
Answer: The total distance traveled by the train is 440 km.
Example 3:
Given: A cyclist travels at a speed of 30 km/hour for 2 hours, and then at a speed of 40 km/hour for the next 3 hours.
Required: What is the average speed of the cyclist for the entire journey?
Equation: Average speed = Total distance / Total time
Solution: Total distance = (30 km/hour x 2 hours) + (40 km/hour x 3 hours) = 60 km + 120 km = 180 km
Total time = 2 hours + 3 hours = 5 hours
Average speed = 180 km / 5 hours = 36 km/hour
Answer: The average speed of the cyclist for the entire journey is 36 km/hour.
Example 4:
Given: A boat travels upstream at a speed of 10 km/hour, and downstream at a speed of 20 km/hour. The speed of the current is 5 km/hour.
Required: What is the speed of the boat in still water?
Equation: Speed of boat in still water = (Speed downstream + Speed upstream) / 2
Solution: Speed downstream = 20 km/hour, Speed upstream = 10 km/hour
Speed of current = 5 km/hour
Speed of boat in still water = (20 km/hour + 10 km/hour) / 2 = 15 km/hour
Answer: The speed of the boat in still water is 15 km/hour.
Example 5:
Given: A car travels a distance of 90 km in 2 hours. If the speed of the car had been 10 km/hour more, it would have taken 1 hour less to cover the same distance.
Required: What is the original speed of the car?
Equation: Distance = Speed x Time
Solution: Let the original speed of the car be x km/hour
Distance traveled at original speed = 90 km
Time taken at original speed = 2 hours
Distance traveled at increased speed = 90 km
Time taken at increased speed = 2 - 1 = 1 hour
Using the equation Distance = Speed x Time, we get:
90 = x * 2
90 = (x + 10) * 1
Solving these equations simultaneously, we get:
x = 40 km/hour
Answer: The original speed of the car is 40 km/hour.