Question 1
Paper 1, no calculatorEasy6 marksA student records the average daily sunlight exposure, hours, and the height after four weeks, cm, of five seedlings of the same species.
| 2 | 3 | 4 | 5 | 6 | |
|---|---|---|---|---|---|
| 11 | 12 | 17 | 17 | 18 |
For these data, the Pearson correlation coefficient is and the regression line of on is
(a)[2]
State the strength and direction of the correlation. State whether this result alone shows that sunlight causes greater height.
(b)[2]
Use the regression line to estimate the height of a seedling receiving 5 hours of sunlight per day.
(c)[1]
Interpret the gradient of the regression line in this context.
(d)[1]
The observed sunlight exposures range from 2 to 6 hours per day. Explain why using the regression line to estimate the height at 10 hours per day may be unreliable.