4.4 ‘Show that ’ questions
In this type of question you are given the answer! All the marks are allocated for correct reasoning and justification.
Suppose you now decide to place your new bath (length 1.7 m, height 0.8 m) against this wall as shown in the diagram below.
Given that you still intend to have the tiles to a height of 1.8 m, this means that you will not need so many tiles now. If a box of twenty-five tiles costs £14.75, show that the cost of tiling this wall will be £457.25. 
Note that the question says ‘show that’. So no marks are allocated for the final cost. This is reflected in the way the marks have been awarded in the following solution to Example 15
Solution to Example 15
This is one of several correct methods of showing that the cost will be £457.25. Any other correct method will also gain full marks.