Every parent desires to equip their child with the best tools for excelling in their PSLE Mathematics exam. One common challenge faced by Primary 6 students is tackling speed questions. That's why we've crafted "Conquering Challenging PSLE Speed Questions in Math: 4 Tips and Tricks to Score Full Marks," a strategic guide designed to help your child master these demanding problems. You'll discover time-tested techniques that demystify speed questions and prepare your child for full-mark success.

## 4 Tips and Tricks to Score Full Marks with PSLE Speed Questions

### 1. Remember the DST Triangle

The DST Triangle is a simple diagram that shows the relationship between distance (D), speed (S), and time (T). In the triangle, 'D' is placed at the top, with 'S' and 'T' at the bottom corners.

Example:

At 10 a.m., Ming Le left Town A and cycled towards Town B at 15 km/h.

He reached Town B at 1 p.m. Find the distance between Town A and Town B.

Solution:

10 a.m. to 1 p.m. â†’ 3 h (Time)

Since Distance = Speed Ã— Time,

15 km/h Ã— 3 h = 45 km

The distance between Town A and B is 45 km.

The logic behind the DST Triangle is that speed is calculated by dividing distance by time (S = D/T). On the other hand, distance can be calculated by multiplying speed by time (D = S x T), and time can be found by dividing distance by speed (T = D/S). By remembering this triangle, students can quickly recall and apply these formulas when tackling P6 speed math questions.

In Paper 1 of the PSLE Math exam, speed questions often test students' understanding of these fundamental relationships. Students can answer these speed questions more efficiently and accurately, leading to better overall performance on the exam. This simple yet powerful tool can serve as a cornerstone for understanding and solving problems related to speed, distance, and time.

### 2. Take Note of the Units Given

Paying close attention to the units offered in maths word problems, particularly when dealing with PSLE speed questions, is crucial to overcoming difficult PSLE speed questions. The units used for speed, distance, and time in these questions might be essential in determining the correct answer.

The most common units used in these types of questions are kilometers (km) for distance, hours (h) for time, and kilometers per hour (km/h) for speed. Understanding the relationship between these units is crucial for solving speed questions. The formula we often use is Speed = Distance/Time. This implies that if the distance is in kilometers and the time is in hours, the speed will be in kilometers per hour.

Where it gets tricky is when the question includes different units. For example, you might be given a distance in meters (m) and a time in minutes (min), but asked to find the speed in km/h. This is where unit conversion becomes critical.

Example:

Mrs Jothi drove at a constant speed of 84 km/h. She completed â…” of her journey in 10 minutes. Find the total distance for her whole journey.

Common mistake: Forgetting to convert minutes to hours. Always look at the units of speed!

Solution:

2 units = 84 km/h Ã— 10/60 h

= 14 km

1 unit = 14 km Ã· 2

= 7 km

3 units = 7 km Ã— 3

= 21 km

The total distance for her whole journey is 21 km.

### 3. Draw Speed Diagrams to Visualise Better

A speed diagram provides a visual representation of the problem at hand, making it easier to understand the relationship between speed, distance, and time. It effectively breaks down the textual information into a simplified visual form, eliminating confusion and potential misinterpretations of the problem.

To draw a speed diagram, you generally create a horizontal line representing the journey from start to finish. This line is divided into sections representing different phases of the journey, allowing you to clearly see how the speed changes over time.

Example:

At 11.00 a.m., a cyclist left park A for park B at an average speed of 28 km/h while a motorcyclist left park B for park A at an average speed of 75 km/h. At 2.15 p.m., they have not passed each other yet and were 24.25 km apart. How far apart was park A from park B?

Note: Notice how by drawing a speed diagram, you are able to see everything at one glance!

28 km/h Ã— 3 15/60 h = 91 km

75 km/h Ã— 3 15/60 h = 243.75 km

91 km + 24.25 km + 243.75 km = 359 km

Park A was 359 km from Park B.

By visualizing the problem in this way, you can better understand what's happening and what you're being asked to solve. This strategy often leads to more efficient problem-solving and increases the likelihood of arriving at the correct answer in PSLE speed questions.

### 4. Look Out for Keywords or Phrases

Carefully read the question and look out for keywords or phrases. These keywords often hold the key to understanding what the problem is asking and which mathematical concept or formula you should use to solve it.

Example 1:

A van left Town A for Town B at 10 00 and travelled at an average speed of 55 km/h. At 13 00, a car left Town A for Town B, travelling at an average speed of 137.5 km/h. How long did the car take to catch up with the van?

KEY CONCEPT: Same direction (Closing Gap)

Keywords: catch up, overtake

Solution:

Tip:

Distance to catch up = Distance travelled by the first object before the second object started its journey

Time taken to catch up = Total distance the car needs to catch up with Ã· Difference in speed

Distance to catch up â†’ 55 km/h Ã— 3 h

= 165 km

Difference in speed â†’ 137.5 km/h â€“ 55 km/h

= 82.5 km/h

Time taken to meet â†’ 165 km Ã· 82.5 km/h

= 2 h

The car took 2 h to catch up with the van.

Example 2:

Town P is 210 km away from Town Q. At 1 p.m., Tom started driving from Town P to Town Q at a speed of 45 km/h while Jerry started driving from Town Q to Town P at a speed of 60 km/h. How long did they take to meet?

KEY CONCEPT: Opposite direction (Closing Gap)

Keywords: meet, passed each other

Solution:

Tip: Time taken to meet = Total distance travelled Ã· Distance travelled by both vehicles in an hour

45 + 60 = 105

210 Ã· 105 = 2

They took 2 h to meet.

PSLE speed questions may be challenging, but they are not insurmountable. The techniques explored in this article â€“ remembering the DST Triangle, understanding units, using speed diagrams, and recognizing important keywords â€“ provide students with a comprehensive strategy to solve these questions effectively.

Each step brings clarity to the problem and helps in careful execution. Keep practicing these techniques, and your child will soon be on their way to scoring full marks in the PSLE Mathematics paper. After all, mathematics is not about memorization but understanding and applying concepts effectively.

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