Higher June 2019 Paper 2 Q10
10. You are given that \(y\) is inversely proportional to \(x\), and that \(y = 124{\cdot}5\) when \(x = 18\).
(a) Find a formula for \(y\) in terms of \(x\). [3]
(b) Use the formula you found in (a) to complete the following table. [2]
| \(x\) | \(\dfrac{1}{2}\) | 18 | |
|---|---|---|---|
| \(y\) | 124·5 | 90 |
| Scheme | Marks | Comments |
|---|---|---|
| \(y \propto 1/x\) OR \(y = k/x\) | B1 | Allow \(y \propto k/x\) |
| \(124.5 = k/18\) or \(k = 2241\) | M1 | FT non linear only |
| \(y = 2241/x\) | A1 | May be seen in part (b), must be sight of \(y = 2241/x\), not for the implied use of this Do not accept \(y \propto 2241/x\) |
| Scheme | Marks | Comments | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| B2 | FT their non linear expression B1 for each value Allow 24.9 given as 25 provided \(k = 2241\) seen in (a) or (b) | ||||||||
| (5) |
Corrected by Westie's Workshop
- The board's mark scheme printed “2241 (as the value of y when x = 18)”. Changed to “124.5” because the question gives y = 124.5 when x = 18; 2241 is the constant k, not the value of y.
Original: see the board's mark scheme PDF (link above).