The '68-95-99.7' rule says
-About 68% of values fall within one standard deviation of the mean.
-About 95% of the values fall within two standard deviations from the mean.
-Almost all of the values — about 99.7% — fall within three standard deviations from the mean.
Here 
Therefore, the probability

The required probability

Answer: option c
Step-by-step explanation: with a two-tailed hypothesis she can find the way to go deep on the study, she will be able to increase the statistical power. She will be able to separate in specifics groups.
X=6 and x=1
You can find your zeros by determining what you have to plug into the function in order for it to equal zero
If we plug in 6, for example we’d get (6-6)(x-1)
Simplified this is 0(x-1)
Anything times 0 is 0, so this is one of our zeros.
Same goes for x-1, we just need to plug in 1 for it to equal 0
Therefore there are zeros at x=1 and x=6 :))