Which of these is expression is equivalent to z+z+z+z

Aresearch company wants to test the claim that a new multivitamin to improve short term memory. state the objective of the experiment, suggest a population, determine the experimental and control groups, and describe a sample procedure.

Find the value of the cosine for angle a

Which term best describes the association between variables a and b? no association a negative linear association a positive linear association a nonlinear association a scatterplot with an x axis labeled, variable a from zero to ten in increments of two and the y axis labeled, variable b from zero to one hundred forty in increments of twenty with fifteen points in a positive trend.