2 The directors of a large company believe that there are more computer failures in the Head Office when temperatures are higher. They obtain data for the Head Office for the maximum temperature, \(T ^ { \circ } \mathrm { C }\), and the number of computer failures, \(X\), on each of 12 randomly chosen days.
- State which of the following words can be applied to \(T\).
Dependent Independent Controlled Response
The data is summarised as follows.
\(n = 12 \quad \sum t = 261 \quad \sum x = 41 \quad \sum t ^ { 2 } = 5869 \quad \sum x ^ { 2 } = 311 \quad \sum \mathrm { tx } = 1021\) - Calculate the value of the product moment correlation coefficient \(r\).
- The directors wish to investigate their belief using a significance test at the \(1 \%\) level.
- Explain why a 1-tail test is appropriate in this situation.
- Carry out the test.
- One of the directors prefers the temperatures to be given in Fahrenheit ( \({ } ^ { \circ } \mathrm { F }\) ), rather than Centigrade ( \({ } ^ { \circ } \mathrm { C }\) ). The relationship between F and C is \(\mathrm { F } = \frac { 9 } { 5 } \mathrm { C } + 32\).
State the value of \(r\) that would result from using temperatures in Fahrenheit in the calculation.