Foundation June 2018 Paper 1 Q15
15.
One day, \(\dfrac{5}{7}\) of the pupils in Year 10 at North High School went on a school trip.
There were 46 pupils in Year 10 who did not go on the trip.
How many pupils are there in Year 10 at North High School? [2]
Alex and Mary go to North High School.
Alex walks \(\dfrac{5}{8}\) of a mile to school. His friend Mary walks \(\dfrac{7}{10}\) of a mile to school.
Mary says,
‘I walk exactly \(\dfrac{3}{40}\) of a mile more than Alex does to school.’
Is Mary correct?
Show calculations to support your decision. [3]
| Scheme | Marks | Comments |
|---|---|---|
| \(\dfrac{46}{2} \times 7\) or equivalent | M1 | May be in steps. |
| 161 (pupils) | A1 |
| Scheme | Marks | Comments |
|---|---|---|
| A correct sum or difference e.g. \(\dfrac{5}{8} + \dfrac{3}{40}\) or \(\dfrac{7}{10} - \dfrac{3}{40}\) or \(\dfrac{7}{10} - \dfrac{5}{8}\) or equivalent | B1 | May be earned later. |
| Sight of two fractions with a common denominator equivalent to any two of \(\dfrac{5}{8}, \dfrac{7}{10}, \dfrac{3}{40}\) | B1 | e.g \(\dfrac{25}{40}, \dfrac{28}{40}\) or \(\dfrac{50}{80}, \dfrac{56}{80}\); May be in a sum or difference e.g. \(\dfrac{25}{40} + \dfrac{3}{40}\) or \(\dfrac{28}{40} - \dfrac{3}{40}\) or \(\dfrac{28}{40} - \dfrac{25}{40}\) Allow any correct common denominator; may imply previous B1 |
| Yes with a correctly evaluated sum or difference appropriately simplified or Yes following sight of \(\dfrac{25}{40}, \dfrac{28}{40}\) or a pair of equivalent fractions | E1 | From a sum or difference, e.g. \(\left(\dfrac{25}{40} + \dfrac{3}{40} = \right)\dfrac{28}{40} = \dfrac{7}{10}\) or \(\left(\dfrac{28}{40} - \dfrac{3}{40} = \right)\dfrac{25}{40} = \dfrac{5}{8}\) or \(\left(\dfrac{56}{80} - \dfrac{50}{80} = \right)\dfrac{6}{80} = \dfrac{3}{40}\) if no sum or difference stated then maximum 2 marks (B0 B1 E1) |
| (5) |
Alternative
Alternative method: (or equivalent in percentages)
| Scheme | Marks | Comments |
|---|---|---|
| 0.7 – 0.625 | B1 | |
| = 0.075 | B1 | |
| Yes with \(\dfrac{75}{1000} = \dfrac{3}{40}\) | E1 |