| Date | May 2009 | Marks available | 3 | Reference code | 09M.1.sl.TZ2.6 |
| Level | SL only | Paper | 1 | Time zone | TZ2 |
| Command term | Predict | Question number | 6 | Adapted from | N/A |
Question
A shop keeper recorded daily sales s of ice cream along with the daily maximum temperature t °C. The results for one week are shown below.
Write down the equation of the regression line for s on t.
Use your equation to predict the ice cream sales on a day when the maximum temperature is 24 °C. Give your answer correct to the nearest whole number.
Markscheme
\(s = 3.56{\text{ }}t - 14.6\) (A1)(A1)(A1) (C3)
Notes: Award (A1) for 3.56.
(A1) for –14.6.
(A1) for s and t.
[3 marks]
\(s = 3.56 \times 24 - 14.6\) (M1)
\(= 70.84\) (70.9) (A1)(ft)
= 71 ice creams (A1)(ft) (C3)
Note: (ft) from candidates answer to (a).
Note: The last (A1) is for specified accuracy, (ft) from their answer.
The (AP) for the paper is not applied here.
[3 marks]
Examiners report
Some candidates attempted to find the equation by hand, generally without success. Those who used their calculator could quickly find the equation and use it to find the number of ice cream sales. A significant number of candidates lost one mark for writing the equation with y and x rather than s and t. A lesser number lost the accuracy mark for an integral number of ice-creams.
Some candidates attempted to find the equation by hand, generally without success. Those who used their calculator could quickly find the equation and use it to find the number of ice cream sales. A significant number of candidates lost one mark for writing the equation with y and x rather than s and t. A lesser number lost the accuracy mark for an integral number of ice-creams.
