If a bacteria spreads its bacteria in a lake for every minute it gets doubled so that it can fill the lake in 20 min .if two bacteria are there how much will they take to fill the lake

Can someone me with this problem i don't understand i need

17. a researcher measures three variables, x, y, and z for each individual in a sample of n = 20. the pearson correlations for this sample are rxy = 0.6, rxz = 0.4, and ryz = 0.7. a. find the partial correlation between x and y, holding z constant. b. find the partial correlation between x and z, holding y constant. (hint: simply switch the labels for the variables y and z to correspond with the labels in the equation.) gravetter, frederick j. statistics for the behavioral sciences (p. 526). cengage learning. kindle edition.

What is the scale factor of two similar pyramids with volumes of 64 cubic feet and 8 cubic feet