Question 830720
let x be the weight of the first man, then
(x +(x+3) +(x+6) +(x+9)) / 4  = 66.5
4x +18 = 4*66.5
4x =  266 - 18
4x = 248
x = 62
our four men are 62, 65, 68, 71 kilos
now to determine the fifth man's weight, we use the following formula
(266 +y) / 5 = 66.5 - 1      y represents the weight of the fifth man
266 + y = 5 * (65.5)
266 + y = 327.5
y = 61.5 kilos
a) weight of heaviest man is 71 kilos
b) weight of fifth man is 61.5 kilos