A cup of tea cools from at minutes to at minutes

MATHEMATICS · Single correct · AP · AP Precalculus · Polynomial and Rational Functions · Polynomial and Rational Functions

Problem

A cup of tea cools from 90∘C90^\circ\text{C} at t=0t=0 minutes to 70∘C70^\circ\text{C} at t=5t=5 minutes. Determine the average rate of change of temperature over this time interval, including the correct sign and units. (a) 4∘C4^\circ\text{C} per minute (b) −20∘C-20^\circ\text{C} per minute (c) −4∘C-4^\circ\text{C} per minute (d) −0.25∘C-0.25^\circ\text{C} per minute

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