Primary Math

Student Resources

P5 Math Common Types of Exam Math Questions: Gaps & Intervals “Tree Planting and Lamp Posts”

Concept: Gaps and Intervals

Common Types of Exam Math Questions

This page contains the common type of PSLE Math concept on Gaps and Intervals. “tree planting” or “lamp posts” questions are commonly tested in school examinations as well as PSLE Math Papers. All Primary 4, Primary 5 and Primary 6 students MUST master these type of questions well.

Hope you can learn from the solution and learn how to solve them.

Take a look at your hand.
Observe the number of fingers and the number of spaces between them.

You will notice that the number of spaces or gaps is always 1 less than the number of fingers.

Let’s have a look at how we apply the concept on gaps and intervals to the tree planting question.

Concept: GAPS AND INTERVALS (Tree Planting)


Desmond owns a 52 coconut trees plantation. He planted the coconut trees at an equal distance apart. The distance between the first coconut tree and the last coconut is 30.6 m. Find the distance between the first and second coconut tree.

Which of the following correctly represent the substances P and Q?

The answer is 60cm

Concept: GAPS AND INTERVALS (Lamp Posts)

There are 30 lamp posts along a street. The distance of the first lamp post to the fourth lamp post is 14.7 m. What is the distance of the street?

Express your answer in metres.

The answer is 142.1m

Have you gain a better understanding of this concept now? I certainly hope you had!