Higher November 2017 Unit 1 Q15
15.
(a) Express \(0{\cdot}6\dot{4}\dot{2}\) as a fraction. [2]
(b) Evaluate \(\left(\dfrac{1}{36}\right)^{-\frac{1}{2}}\). [2]
| Scheme | Marks | Comments |
|---|---|---|
| \(x = 0{\cdot}6424242\ldots\ldots\) \(100x = 64{\cdot}24242\ldots\ldots\) with an attempt to subtract | M1 | Or \(10x\) and \(1000x\), or equivalent. |
| 636/990 or 106/165 or equivalent | A1 | C.A.O. (63·6/99 gets M1 A0). ISW. |
Alternative method
| Scheme | Marks | Comments |
|---|---|---|
| (0·6+0·0424242...=) 6/10 + 42/990 or equivalent | M1 | |
| 636/990 (= 106/165) | A1 | ISW |
| Scheme | Marks | Comments |
|---|---|---|
| 6 | B2 | B1 for \(36^{\frac{1}{2}}\) or √36 or \((36/1)^{\frac{1}{2}}\) or \((1/6)^{-1}\) or 1/(1/6) Allow SC1 for an answer of – 6. |