Solve speed questions easily
When it comes to preparing for PSLE math, speed always comes up as one of the most challenging Primary 6 topics according to most students and parents.
In this simple Practicle guide on speed, let’s look at the different kind of speed questions that can appear in your PSLE math paper and learn how to solve them.
Here’s what we’ll cover:
The only speed formula you’ll need
Let’s start with the Speed questions you’ll see in Paper 1.
These Math problems usually test you on your basics. Most of the time, they can be solved with the Speed Time Distance formula (Also known as Time Speed Distance formula or Distance Speed Time formula, they are all the same).
Let’s look at each ingredient of this formula:
- Speed – Speed measures how fast an object travels from one place to another. (usually in m/s or km/h)
- Time – Time is how long the object takes to travel
- Distance – Distance measures how far the object travels
If you are driving a car at a speed of 60 km/h, this means that the car is going to travel 60 km every hour. When you drive it for 2 hours, you would have covered a total distance of 60 km/h x 2 h which is 120 km.
This is why distance = speed * time and knowing this relationship between speed, time and distance is key to solving any speed question.
Speed Questions in Math Paper 1
Now let’s see how a speed question in your PSLE Paper 1 might look like. These speed questions will provide you with 2 known values out of the 3 ingredients most of the time. The missing third value that you are asked to solve can either be the speed, time or distance.
For example, you might be asked to solve a question about speed like this:
Alvin was walking at an average speed of 70 m/min. At this speed, how long did he take to walk a distance of 910 m?
Source: St Nicholas Girls Primary, Primary 6 Prelim Exam Paper
As you can see, we have both the speed and distance in this Math problem. How can we make use of these information to solve for the time?
This is where our distance speed time formula comes in (refer to DST triangle below).
To solve this question, we’ll need to adjust our formula a little so that it becomes this!
Time = Distance / Speed
When we replace the known values into this formula, we can easily calculate the time Alvin took by dividing the distance of 910 m by his speed of 70 m/min. This gives us an answer of 13 min. Did you get that?
Next, let’s look at the speed questions that may appear in your PSLE Paper 2. This is where things start to get a bit more complicated.
Speed Questions in Math Paper 2
For PSLE speed questions in Paper 2, you might start seeing word problems that involve 1 object moving and stopping along its journey, 2 objects that starts from the same point and move in different directions, 2 objects that are trying to catch up with one another etc.
Yes, that can be VERY confusing to our Primary 6 students.
Let’s look at an example of one such challenging speed question in Practicle which is similar to what you might see in your exams.
Aladdin and Jasmine were having a race on their magic flying carpets. They left the same starting point for the market at 13 00. Both of them did not change their speed throughout the journey. Aladdin travelled at a constant speed of 60 km/h. When he reached the market at 13 30, Jasmine was 3 km from the market. What is Jasmine’s speed?
Now while reading this Math problem, many kids would already start thinking to themselves “This sounds super hard! Who’s travelling where?!?!”
Luckily, there’s a way to simplify this entire complicated-sounding speed problem!
Want to know what it is? Let’s jump to the next section where we’ll teach you a useful problem-solving technique called the “draw a diagram” strategy to help you solve such speed questions easily.
How drawing speed diagrams can save your day
Whenever you come across a Math problem on speed that sounds super complicated, draw the speed diagram to help you see what’s happening! This is going to make things so much easier!
As you are drawing the speed diagram, you are breaking down the problem step by step. This helps you get rid any any confusion that you might have! Besides that, identifying the key people/objects involved, their locations and also their travel paths helps you understand their relationship better. As a result, you can focus on the Mathematical and problem solving aspects of the problem.
Check out this Practicle Math video that we’ve created to learn the steps to draw a speed diagram with an example question on speed!
Try drawing speed diagrams to represent the problems on speed today and see how it helps you solve these problems faster.
Alright, now that you’ve learnt how to solve the different kinds of speed questions that you might see in your Primary 6 PSLE Math exam, how confident are you in getting that AL1?
If you need more speed questions to practice on, check out Practicle where we have unlimited exam questions to help you polish up your Math skills, along with video explanations from school teachers!