Laetisaric acid is a compound that holds promise for control of fungus diseases in crop plants. The accompanying data show the results of growing the fungus Pythiumultimum in various concentrations of laetisaric acid. Each growth value is the average of four radial measurements of a P. ultimum colony grown in a petri dish for 24 hours; there were two petri dishes at each concentration.9
(a) Consider testing whether the population correlation is zero. How many degrees of freedom are there for the test?
(b) Compute the value of the test statistic.
(c) The P-value for the test is 2.3 × 10-9. If a = 0.05, state your conclusion regarding the null hypothesis in the context of this setting.

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Laetisaric acid concentration Fungus growth Y (mm) 33.3 31.0 29.8 27.8 28.0 29.0 10 10 18.3 15.5 11.7 10.0 23.642 7.8471 Mcan SD 11.500 10.884 r =-0.98754