Intermediate November 2021 Unit 1 Q11
11.
(a) Find the Lowest Common Multiple (LCM) of 60 and 72. [2]
LCM of 60 and 72 is …………………
(b) Express 882 as a product of its prime factors.
Give your answer in index form. [3]
Give your answer in index form. [3]
| Scheme | Marks | Comments |
|---|---|---|
| 360 | B2 | Mark final answer. B1 for 23 × 32 × 5. OR B1 for any other common multiple e.g. 720, 1080 etc. unambiguously identified as a final answer. OR B1 for sight of correct prime factors e.g. 60 = 22 × 3 × 5 or equivalent. AND 72 = 23 × 32 or equivalent. OR Accurate Venn diagram showing correct prime factors. OR B1 for sight of 60, 120, 180, 240, 300, 360, …. AND 72, 144, 216, 288, 360 with no further numbers |
| Scheme | Marks | Comments |
|---|---|---|
| For a single method that produces 2 prime factors from the set {2, 3, 3, 7, 7} before the 2nd error. | M1 | Must be a method of ‘repeated division’. |
| 2, 3, 3, 7, 7 | A1 | C.A.O. For sight of the five correct factors (Ignore 1s) |
| 2 × 32 × 72 | B1 | F.T. ‘their primes’ provided at least one index form used with at least a square. Do not F.T. non-primes. Allow (2)(32)(72) and 2.32.72 Do not allow 2,32,72. Inclusion of 1 as a factor gets B0. |