If the standard deviation of x is 15, the covariance of x and y is 94.5, the coefficient of correlation r = 0.90, then the variance of y is 7.0. a. true b. false

We have the formula

From the above formula,

That is variance of Y is 49 not 7.

Hence the statement is (b) False

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this

6mm^3 or .6cm^3

      216

      /   \

  36     6

  /   \     /

6     6   6

factor trees are nice.