BIG Corporation produces just about everything but is currently interested in the lifetimes of its batteries, hoping to obtain its share of a market boosted by the popularity of portable CD and MP3 players. To investigate its new line of Ultra batteries, BIG randomly selects 1000 Ultra batteries and finds that they have a mean lifetime of 949 hours, with a standard deviation of 83 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 35%/56%/75%/84%/89% ) of the lifetimes lie between 783 hours and 1115 hours.(b) According to Chebyshev's theorem, at least 84% of the lifetimes lie between ... hours and ... hours (Round your answer to the nearest whole number.)