Thursday, March 23, 2017

POTW #24 - Back at it!

Welcome back to the POTW after a short (March) break. Please find the answers and new questions below:


GR. 7 POTW #24 Question:





Gr. 8 POTW #24 Question:


Gr. 7 POTW #23 Solution:



Gr. 8 POTW #23 Solution:

9 comments:

  1. Maxwell, Avi, Daniel Grade 7 POTW:

    The answer is 40 km/h for the truck. We did our work on paper.

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  2. Grade 7 POTW:
    At first I used guess and check to figure it out, but I wasn't sure if the answer was right so I managed to figure out an answer using a good strategy.

    First of all, I will figure out how much distance in total the motorcycle went.
    Since the time is 1 and 1/4 hours, I decided to change it into decimals, even though it actually doesn't make a difference.

    60 * 1.25 = 75
    This shows that the motorcycle was driven 75 km.

    Because the motorcycle traveled 25 km more than what the truck did, this means that the truck moved 75-25=50 km.

    So, how are we supposed to figure out what the speed was per hour?
    Well, there are actually two ways that come up to the same answer.

    The first way is about the same as the second way, but since we are doing our algebra unit, I will use Algebra!!!
    Let x be the speed of the truck per hour
    5/4x= 50
    Divide by 5/4 on both sides...
    x = 50 / 5/4
    Flip the fraction so that it is multiplication...
    50*4/5 = 40 km.

    Therefore, the answer is that the truck moved at a speed of 40 km per hour.

    The other way is simple. You divide 50 by 1.25 since that is the time the truck moved for, and it moved 50 km in total. The formula is Speed of the truck per hour multiplied by the time gives you the total distance.

    Since we have the total distance, which is 50 km, and the time, which is 1.25 hours, I use the formula, but divide to get the speed.
    50/1.25=40
    Therefore, the answer is 40 km as well, proving that my answer is correct.

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  3. Ameya and Aleks' Solution To The Grade 7 POTW:
    We know that the difference between the truck and the motorcycle is 25 km. The motorcycle travels at 60 km/h, but the total time spent driving is 1 hour and one quarter. Since an hour consists of 60 minutes, 60 divided by 4 to give us a quotient of 15. To find the total distance traveled by the motorcycle we need to add these 2 numbers together. This means that the motorcycle traveled 75 km in total. Now we need to deal with the truck distance. In order to find the distance traveled by the truck, we subtract 25 from 75. We do this because the motorcycle ended up 25 km ahead of the truck. That gives us a difference of 50. Now we have to remember that the motorcycle and truck traveled 1 and 1/4 of a hour. This means that the number must be 40. 40 km/h is the speed of the truck. This is because 1/4 of 40 is equal to 10. Because of this we can add the two numbers together and get 50. This means that the truck traveled at a speed of 50 km/h.

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  4. I got an answer of 378km.

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  5. The speed of the truck is 40 km and hour. First we have to find how far the car motorcycle travels. Since they drive for an 1 1/4 hours we take 60 and add 15 to 60 to get the total kilometers the motorcycle travels. Then subtracting 25 we know that the truck travels 50 km. Then knowing how 40+1/4(10)=50 I can conclude the truck travels at a speed of 40 km an hour.

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  6. Grade 7 POTW

    Because the average speed of the motorcycle is 60 km an hour, it must be 75 km in an hour and 15 minutes. Since the motorcycle was 25km farther, the truck must have gone 50 km in 75 minutes. Dividing that into 5 parts (15 minutes each), means that the truck went 10km in 15 minutes. Multiplied by 4, the average speed of the truck was 40km per hour.

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  7. The truck goes 40km/h. We know the motorcycle goes 75 minutes, since 1 1/4 hours is 60+15. Then we subtract 25 because the motor cycle was 25 km farther than the truck. So then we have 50, since they both traveled for 1 1/4 hour, 1/4 of 40 is 10, 10+50=60. So we know the truck goes at 40 km per hour.

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  8. The truck speed was 40 km/h

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  9. The average speed of the delivery truck was 40 km/h.
    To figure this out, I used the formula of distance = speed * time and speed = distance / time. I already know that both the motorcycle and delivery truck drove for 1.25 hours. I also know how fast the motorcycle goes on average. So, plug in all the numbers to the required variable. distance = 60 * 1.25 distance = 75
    Now for the truck. As stated in the question, the motorcycle travels 25 km farther than the truck. Since we know that the motorcycle traveled 75 km I simply subtracted 25 to get 50 km. The truck traveled 50 km in 1.25 hours.
    Speed = Distance / Time Plug in the numbers given.
    Speed = 50 / 1.25 Speed = 40 km/h
    Therefore, the average speed of the delivery truck was 40 km/h.
    :DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

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