Two sets of chromium analyses were performed on water samples from a stream that runs near a chromium plating plant:
Before the spill After the spill
Mean: 0.95 ppm Cr 1.10 ppm
N 5 6
S 0.05 ppm 0.08 ppm
Could it be stated, at the 95% confidence level, that after and before the spill there was no difference in the chromium level in the stream?