Internet Academy

At a construction site, 3 workers need to take the elevator to the top floor to do repairs. The elevator can carry only 300 pounds at most. Mr. Andrews weighs 150 pounds, Ms. Baker weighs 145 pounds, and Mr. Cass weighs 235 pounds. One person must always be in the elevator to operate it.

Tell how these 3 people can use the elevator to get to the top floor so that they can work on the job together.

Clearly explain the steps needed to solve the problem using words, numbers, and/or pictures.

The response needed for this problem is a short answer response worth 2 points.

Problem solving strategies that you may be able to use for a problem like this could be to draw a simple picture, where you draw or show the workers going up and down using arrows. You will need to use some logical reasoning to help you solve this one as you won't be just adding or subtracting, but you will need to do a little of it. You could act out the problem using family members or even stuffed animals to help! You could also use objects to help assist you, maybe using toothpicks to represent the workers. No matter what strategy you use, you will come up with an answer something like the one below. Let's take a look at how you would be scored on a problem like this one.

In order to receive the full 2 points for this problem you would need to use a viable strategy to construct a solution of how all 3 workers can get to the top floor without going over the 300 pound elevator limit.

For example, one way way to solve this may be the following:

Mr. Andrews (150 pounds) and Ms. Baker (145 pounds) need to go up first.
One of them must come back down.
Mr. Cass (235 pounds) goes up alone.
When Mr. Cass reaches the top, the other person weighing about 150 pounds (Mr. Andrews or Ms. Baker) must go back down.
Then the remaining two can ride up together.

Student example:

Since Mr. Andrews and Ms. Baker weighs 150 and 145 pounds, their combined weight is 295, so they can both be on the elevator at the same time (145 + 150 = 295) They can all go to the top floor if: Mr. Andrews and Ms. Baker go on the elevator first. Then Ms. Baker goes down. Then Mr. Cass goes up. Then Mr. Andrews goes down. Then both Ms. Baker and Mr. Andrews go up.

Remember, this only one way that this one could be solved. You can see how there could be other orders or ways to solve this one.

To receive 1 point for an answer, it would include only one of the following:

You give a flawed explanation of how all 3 workers can get to the top floor. You don't put all 3 workers in the elevator at one time but sends the elevator down without an operator.
You give an incomplete or vague explanation but it doesn't contain errors. The response must indicate an understanding of 3 of the 5 elevator trips required.

Student example:

150 + 145 + 235 = 530 together
150 + 145 = 295
235 + 150 = 385

Mr. Andrews and Mrs. Baker may go first then Mr. Cass may go when they get back.

Example 2 >>