Question

There are 1, 40, 00, 000 pencils of lengths ranging from 3 to 6 inches and are put up straight. the average length of 80% of pencils is 5 inches. calculate the total length spanned by the pencils

Answer 1

80% of 14000000 = 11200000
length covered 5 inches pencils = 11200000*5 = 56000000
20% of 14000000 = 2800000
length covered 3 inches pencils = 2800000*3 = 8400000
length covered 6 inches pencils = 2800000*6 = 16800000

so total length 
min : 56000000 + 8400000 = 64400000 inches TO
max : 56000000 + 16800000 = 72800000 inches