| Date | May 2012 | Marks available | 2 | Reference code | 12M.1.sl.TZ2.3 |
| Level | SL only | Paper | 1 | Time zone | TZ2 |
| Command term | Estimate | Question number | 3 | Adapted from | N/A |
Question
Consider the following values of x and y and the scatter diagram which represents the information given in the table.
Write down the value of
(i) a ;
(ii) b .
The mean of the x values is 5 and the mean of the y values is 4. Draw the line of best fit on the scatter diagram above.
Use your line of best fit to estimate the value of y when x = 6.5.
Markscheme
a = 8, b = 5 (A1)(A1) (C2)
Note: Award (A0)(A1)(ft) if a = 5, b = 8 .
[2 marks]
(A1)(A1) (C2)
Note: Award (A1) for straight line passing through (5, 4), (A1) for y-intercept between 6.8 and 8, if necessary with the line extended.
[2 marks]
3.1 (±0.3) (M1)(A1)(ft) (C2)
Note: Award (M1) for an indication of use of their line of best fit (dotted lines or some indication of mark in the correct place on graph). Accept y = 3.1 ± 0.3.
[2 marks]
Examiners report
Most candidates could find the values of a and b, draw the line of best fit and find an estimate of the value of y. Follow through marks could be awarded in part (c) with an incorrect line of best fit, if dotted lines were shown on their graphs, indicating their method.
Most candidates could find the values of a and b, draw the line of best fit and find an estimate of the value of y. Follow through marks could be awarded in part (c) with an incorrect line of best fit, if dotted lines were shown on their graphs, indicating their method.
Most candidates could find the values of a and b, draw the line of best fit and find an estimate of the value of y. Follow through marks could be awarded in part (c) with an incorrect line of best fit, if dotted lines were shown on their graphs, indicating their method.
