Difficulty: Rating: GCSE Marks:

GCSE Text:
As part of a DIY project, Shem has started to build a wooden wall that consists of upright posts, supporting horizontal planks in between. The overall distance between the centres of the outside two posts is 14.15m.  The planks he has ordered are 2.4m in length.

a) Calculate how many upright posts he will need in total to complete the wall?

b) What will be the distance between the centres of each post?

Suggestions:
This is a question that encourages students to sketch the solution to visualise the problem, and as it is not easy to grasp initially, students will need to model resilience. Students need to realise that there will be waste per plank to achieve the overall distance, and need to round carefully to decide how many posts are needed. It is important to stress to students that given the high marks awarded for a question of this type, even if the overall method proves too difficult for them, method marks will be awarded for working out any of the following:

• Correct use of division

Extension Ideas:
Teachers could extend the learning by considering:

• If Shem had space, how much extra width of wall could he achieve by not cutting each of the horizontal planks?
• If the height of the wall needs to be within 10cm of 2.5m, and the height of each horizontal plank is 28cm, how many planks will be needed to complete this wall?