At 1:00 pm the temp is 72 deg, the temp went down to 52 deg at 6:30, what is the temp at 4:00pm?
Temperature change is seldom linear, be we can assume so.
Let time t be hours after 1PM
T(timet)=mt+b
at t=0
72=m*O+b
T(t)=mt+72
m= (52-72)/5.5=-20/5.5
T(4pm)=-20/5.5 *3+72=72-60/5.5=61deg