Intermediate November 2017 Unit 2 Q3
3.
(a)
The mode and the median of all seven numbers are both the same.
Find one possible number that can be written on the blank card. [1]
11 23 5 9 18 20
A number is to be written on the blank card.The mode and the median of all seven numbers are both the same.
Find one possible number that can be written on the blank card. [1]
Number on card …………
(b) One extra number is added to the following list of three numbers.
What number was added to the list? [4]
6 8 13
The mean of the new list of four numbers is 1 less than the mean of the original three numbers.What number was added to the list? [4]
Number added …………
| Scheme | Marks | Comments |
|---|---|---|
| 11 OR 18. | B1 | B1 for either or both. Answer space takes precedence. |
| Scheme | Marks | Comments |
|---|---|---|
| (Original mean = ) 9 | B1 | From (6 + 8 + 13) ÷ 3. |
| (New mean = 9 – 1 =) 8 | B1 | F.T. ‘their derived or stated original mean’ – 1. Do not allow 27 – 1 = 26 as a new mean for this B1. Unambiguously showing ‘new mean’ = 8 gains B1B1 |
| (New total = 8 × 4 = ) 32 | B1 | F.T. ‘their derived or stated new mean’ × 4. Unambiguously showing ‘new total’ = 32 gains B1B1B1 |
| (Number added = ) 5 | B1 | F.T. ‘their identified new total’ – 27. Answer space takes precedence for final answer. A final answer of 5 implies all four B1 marks. |