Home » mcq » statistics » The following table shows the distribution of life time of 350 radio tubes : Lifetime in hrs 300-400 400-500 500-600 600-700 No. of tubes 6 18 73 165 Lifetime in hrs 700-800 800-900 900-1000 No. of tubes 62 22 4Assuming that class frequencies are evenly distributed within the corresponding classes, find the percentage of tubes having life time between 650 hours and 850 hours