Question 1 - A-Level Maths

Exam Board	AQA
Module	S1 (Statistics 1)
Year	2008
Session	June
Topic	Linear regression
Type	Calculate regression line then predict

1 The table shows the times taken, \(y\) minutes, for a wood glue to dry at different air temperatures, \(x ^ { \circ } \mathrm { C }\).

\(\boldsymbol { x }\)	10	12	15	18	20	22	25	28	30
\(\boldsymbol { y }\)	42.9	40.6	38.5	35.4	33.0	30.7	28.0	25.3	22.6

Calculate the equation of the least squares regression line \(y = a + b x\).
Estimate the time taken for the glue to dry when the air temperature is \(21 ^ { \circ } \mathrm { C }\).