Answer:

Step-by-step explanation:

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:
.
Step-by-step explanation:
We want to convert the function into the form that let's us easily find the x-intercept, and it would be for the form
because then we can find the x-intercept in the following manner:



We factor our function
and get

Now this form let's us easily find the x-intercepts:


and so we pick the second choice: f(x)=(2x+1)(2x-1).