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 936 hours, with a standard deviation of 80 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) V of the X ? lifetimes lie between 776 hours and 1096 hours. (b) According to Chebyshev's theorem, at least 56% of the lifetimes lie between ] hours and I hours. (Round your answer to the nearest whole number.)