A) 4
B) 5
C) 6
D) 7
Correct Answer: A
Solution :
According to Newton?s law of cooling in first case, \[\frac{75-65}{t}=K\left[ \frac{75+65}{2}-30 \right]\] ?..(i) in second case,\[\frac{55-45}{t}=K\left[ \frac{55+45}{2}-30 \right]\] ?..(ii) Dividing eq. (i) by (ii) we get \[\frac{5t}{10}=\frac{40}{20}\]Þ\[t=4\]minutesYou need to login to perform this action.
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