Higher June 2018 Paper 1 Q9
9 The range of a set of numbers is \(\;15\dfrac{1}{4}\)
The smallest number is \(\;-2\dfrac{7}{8}\)
Work out the largest number. [3 marks]
| Answer | Mark | Comments |
|---|---|---|
| Alternative method 1 | ||
| \(-2\dfrac{7}{8} + 15\dfrac{1}{4}\) or \(15\dfrac{2}{8}\) or (\(-\))2.875 and 15.25 or (\(-\))\(\dfrac{23}{8}\) and \(\dfrac{61}{4}\) | M1 | oe common denominator for both fractional parts of the mixed numbers conversion of both numbers to decimals with at least one correct conversion of both numbers to improper fractions with at least one correct |
| \(-2\dfrac{7}{8} + 15\dfrac{2}{8}\) or \(-2.875 + 15.25\) or \(-\dfrac{23}{8} + \dfrac{122}{8}\) | M1dep | oe common denominator correct decimals oe common denominator |
| \(\dfrac{99}{8}\) or \(12\dfrac{3}{8}\) or 12.375 | A1 | oe fraction, mixed number or decimal |
| Alternative method 2 | ||
| \(-2 + 15\) and (\(-\))\(\dfrac{7}{8} + \dfrac{1}{4}\) | M1 | |
| \(-2 + 15\) and (\(-\))\(\dfrac{7}{8} + \dfrac{2}{8}\) or \(13 - \dfrac{5}{8}\) | M1dep | oe common denominator |
| \(\dfrac{99}{8}\) or \(12\dfrac{3}{8}\) or 12.375 | A1 | oe fraction, mixed number or decimal |
Additional guidance
| \(15\dfrac{1}{4} - -2\dfrac{7}{8}\) scores M0, but followed by \(15\dfrac{2}{8} + 2\dfrac{7}{8}\) scores M1 on Alt 1 | |
| Values in 2nd mark must be correct; no ft from incorrect conversion | |
| \(\dfrac{99}{8}\) incorrectly converted to a decimal or mixed number | M1M1A1 |
| \(13\dfrac{-5}{8}\) | M1M1A0 |