Last week, the thickness of the ice on a lake increased by (25)/(t+3) centimeters per day (where t is the number of days since the ice first formed). By how may centimeters did the thickness of the ice increase between t=0 and t=4?
t = 0 + t =1 + t = 2 + t = 3 + t = 4
25/3 + 25/4 + 25/5 + 25/6 + 25/7 = 27.32 cm ( this includes day 0 and day 4 increases in thickness)
BETWEEN days 0 and 4 would only include days 1 2 3 ( the red ones above) = 15.42 cm Not sure which answer is the one you want