| Date | May 2016 | Marks available | 2 | Reference code | 16M.1.sl.TZ2.2 |
| Level | SL only | Paper | 1 | Time zone | TZ2 |
| Command term | Find | Question number | 2 | Adapted from | N/A |
Question
There are 10 items in a data set. The sum of the items is 60.
The variance of this data set is 3. Each value in the set is multiplied by 4.
Find the mean.
(i) Write down the value of the new mean.
(ii) Find the value of the new variance.
Markscheme
correct approach (A1)
eg\(\,\,\,\,\,\)\(\frac{{60}}{{10}}\)
\({\text{mean}} = 6\) A1 N2
(i) new mean \( = 24\) A1 N1
(ii) valid approach (M1)
eg\(\,\,\,\,\,\)\({\text{variance}} \times {(4)^2},{\text{ }}3 \times 16\), new standard deviation \( = 4\sqrt 3 \)
new variance \( = 48\) A1 N2
[3 marks]
Examiners report
While most candidates were able to answer part (a) of this question correctly, they were not as successful in part (b). It seems that the item on the Maths SL syllabus dealing with the "effect of constant changes to the original data" was skipped over in many schools.
While most candidates were able to answer part (a) of this question correctly, they were not as successful in part (b). It seems that the item on the Maths SL syllabus dealing with the "effect of constant changes to the original data" was skipped over in many schools.
