For 18 randomly selected towns, the sample product moment correlation coefficient between mean daily temperature and daily electricity use is r=−0.492r=-0.492r=−0.492. A one-tailed critical value at the 5% significance level is -0.4000.
Carry out a test for negative correlation.
178 exam-style questions on WJEC A Level Maths 4.3.1 Statistical hypothesis testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.