BIG Corporation produces just about everything but is currently interested in the lifetimes of its batteries. To investigate its new line of Ultra batteries, BIG randomly selects 1000 Ultra batteries and finds that they have a mean lifetime of 853 hours, with a standard deviation of 84 hours.. Suppose that this mean and standard deviation apply to the population of all Ultra batteries. Complete the following statements about the distribution of lifetimes of all Ultra batteries.

(a)According to Chebyshev's theorem, at least (Choose one) of the lifetimes lie between

727

hours and

979

hours.

(b)According to Chebyshev's theorem, at least (Choose one) of the lifetimes lie between

685

hours and

1021

hours.