The average daily temperature from 9th to 16th January(both inclusive) was 38.6 C and that from the 10th to 17th January(inclusive) was 39.2 C. what was the temperature on 17th January?
I am able to find total temperature as 308.8 C from from 9th to 16th January and 313.6 C from the 10th to 17th January but stuck !!!
The solution of this problem would require some additional information, e.g. the temperature $t_9$ on January 9th. Knowing this, and calling $t_{17}$ the temperature on January 17th, we would have
$$313.6-308.8=t_{17}-t_9$$
$$t_{17}=t_9+4.8$$