You don't use a calculator at all. Calculators won't take the place
of learning what's going on.

Instead of thinking the calculator will keep you from having to
learn the material, you must instead learn what the 68-95-99.7 rule 
is all about.

According to the 68-95-99.7 rule, 

1.  we expect 68% of the observations in the data set to fall
    between 1 standard deviation below the mean and 1 standard 
    deviation above the mean.

2.  we expect 95% of the observations in the data set to fall
    between 2 standard deviations below the mean and 2 standard 
    deviations above the mean.    

3.  we expect 99.7% of the observations in the data set to fall
    between 3 standard deviation below the mean and 3 standard 
    deviation above the mean.

You are asked to fill in these blanks:

We expect 68% of the observations in the data set to fall
between       and      .

So by the rule, we subtract 1 standard deviation 1.1 from the mean 6.8

and get 6.8 - 1.1 = 5.7  to go in the first blank, and

we add 1 standard deviation 1.1 to the mean 6.8 

and get 6.8 + 1.1 = 7.9  to go in the second blank.

we expect 68% of the observations in the data set to fall
between  5.7  and  7.9 .

Edwin