Answer:
1) Less than 13.6%
2) Less than .1%
3)RockReady
Step-by-step explanation:
THe standar deviation is a measure in statistics used to expres the dispersion of a set of values, so the standar deviation normally includes 34.1% of the values up and down the scale, so for example In Dura tunes 34.1% of the batteries would have 9 to 13 hours of battery life, to go down to 8 hours you would have to scale to the next deviation and that is of 13.6%, in RockReady is of 1.5 hours, and you would have to go down till the deviation of .1% to find the 4 hours needed in order for the batteries to have a battery life of 8 hours, that is why the best option statistically would be Rock Ready.