To investigate the relationship between intracellular calcium and pulse-rates, researchers measured the free calcium concentration in the blood platelets of 38 people. They also measured the pulse rate for each person. Suppose the mean pulse rate for all people is 72 bpm with a variance of 16. What is the probability that the sample mean is less than 70 bpm

he used the algebra tiles correctly.

step-by-step explanation:

given : 3x(2x-1)

solution :

since he used algebra tiles .

armando's solution is the same in the solution shown in figure

as he distributed 2x into x and x and wrote them vertically

and also write   -1 vertically

and 3x into x and x and x and wrote it horizontally

performing the multiplication in the algebra tiles we get

and solving the given expression :

3x(2x-1)

since solving the expression using tiles   and solving the expression algebraically we get the same answer

thus   we can choose the first statement as the answer to this problem which is "he used the algebra tiles correctly".

the answer is c. 23/3