Higher November 2018 Paper 1 Q23
23 Prisms A and B are similar.
The cross sections are shaded.
area of the cross section of A : area of the cross section of B = 4 : 9
Work out the area of the cross section of B. [5 marks]
| Answer | Mark | Comments |
|---|---|---|
| Alternative method 1 | ||
| \(\sqrt{4} : \sqrt{9}\) or 2 : 3 | M1 | length A : length B |
| \(30 \div\) their \(3 \times\) their 2 or 20 | M1dep | length A |
| \(480 \div\) their 20 or 24 | M1dep | area cross section A |
| their \(24 \div 4 \times 9\) | M1dep | |
| 54 | A1 | |
| Alternative method 2 | ||
| \(\sqrt{4} : \sqrt{9}\) or 2 : 3 | M1 | length A : length B |
| \((\sqrt{4})^3 : (\sqrt{9})^3\) or 8 : 27 | M1dep | volume A : volume B |
| \(480 \div\) their \(8 \times\) their 27 or 1620 | M1dep | volume B |
| their \(1620 \div 30\) | M1dep | |
| 54 | A1 | |