Answer:
B. 95% confident the average concentration of PCBs in the water supply is between 2.9 ppb and 3.5 ppb
Step-by-step explanation:
You are given the total number of samples, the concentration of lead, and the standard deviation. The standard deviation represents how inaccurate the estimation of the concentration of lead in the drinking water. This means that there can only possibly be a 0.3 ppb error in the estimation. 3.2-0.3=2.9, and 3.2+0.3=3.5
The correct answer is B. -12
Answer:
It's C
Step-by-step explanation:
Your graph should be this one, with both lines solid because, the X line, or red, has to be at least -1 or higher, and the Y line, or the blue, has to be +4 or higher
5x^2 -15x-140
5(x² -(3x) -28)
5(x² +(4x-7x)-28)
5(x(x+4) -7(x+4)
5(x-7)*(x-4)
