16   6. Anna is investigating the relationship between exercise and resting heart rate. She takes a random sample of 19 people in her year at school and records for each person • their resting heart rate, h beats per minute • the number of minutes, m, spent exercising each week Her results are shown on the scatter diagram. 0 400 200 80 70 60 h m (a) Interpret the nature of the relationship between h and m (1) Anna codes the data using the formulae x = log10 m y = log10 h The product moment correlation coefficient between x and y is – 0.897 (b) Test whether or not there is significant evidence of a negative correlation between x and y You should • state your hypotheses clearly • use a 5% level of significance • state the critical value used (3) The equation of the line of best fit of y on x is y = – 0.05x + 1.92 (c) Use the equation of the line of best fit of y on x to find a model for h on m in the form h = am k where a and k are constants to be found. (5) Turn over 17   Question 6 continued _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________