Jess wants 200 ribbons of length 110 cm for a party. However, the ribbons were sold at 25 m per tape. How many tapes will Jess need?
Why is this PSLE ribbon question tricky to some students?
Noticing different units of measurements
If you are a student who’s taking the 2020 PSLE Math exam, you might be feeling nervous and not notice that the units of measurement that are given are different. The length of the ribbons needed is measured in centimetres (cm) while the length of the tape is given in metres (m).
If you make the careless mistake of forgetting to convert the units of measurement to a common one, you will be working with the wrong numbers and end up getting your answer wrong.
2. Misinterpreting the question
If you didn’t read the question carefully, you might think of by multiplying 200 by 110 cm to find the total length of ribbon Jess needs and then dividing that answer by 2 500 cm to get the number of tapes needed.
This cannot be done because the leftovers of each roll of tape cannot be put together to form ribbons of 110 cm.
3. Making the right decision when it comes to rounding up or down
There are 2 important decision making points that will affect our answer as we work out the problem.
When we divide 2500 cm by 110 cm to find the number of ribbons that can be cut from each tape, should we round our answer up or down?
Also, after dividing the number of ribbons that we need by the number of ribbons that can be cut from one tape, we need to decide if we should round our answer up or down again.
Making the wrong decision at any of these points is going to cause us to get the wrong answer.
Answer to this PSLE ribbon question:
To answer this PSLE ribbon question correctly, you need to take note of the units involved and apply important critical thinking skills when it comes to cutting the ribbons.
If you want to learn how to get the answer to this question and avoid all the booby traps, check out this Math video that we’ve prepared!
How did you find this PSLE 2017 Math question? Was it easy or difficult for you? Let us know in the comments below.