Certain quantity of water cools from 700C to 600C in the first 5 min and to 54°C in the next 5 min. Thetemperature of the surrounding is

Let temperature of surrounding be Q0  then from Newton's law of cooling Case I  Q2−Q1t=KQ2+Q12−Q070−605=K65−Q0                                      …(i) Case II  60−545=57−Q0K                       …(ii)On dividing Eq. (i) by Eq. (ii), we get106=65−Q057−Q0⇒Q0=45∘C