Question

13. The mean temperature from the 9th to the 16th
of January, both days inclusive, was 11.6°C and
from the 10th to the 17th was 12.2°C. The
temperature on the 9th was 10.8°C. What was it
on the 17th?​

Answer 1

Temperature on the 17th of January is 15.6°C.

Step-by-step explanation:

We are given that the mean temperature from the 9th to the 16th  of January, both days inclusive, was 11.6°C and  from the 10th to the 17th was 12.2°C.

Also, the  temperature on the 9th was 10.8°C.

As we know that Mean formula, $\bar X = \frac{\sum X}{n}$

where, $\sum X$ = Total Sum of n observation

                  n = Number of observation

So, Total Sum of n observation ($\sum X$) = $\text{Mean} (\bar X) \times \text{Number of observation} (n)$

Total Sum of all temperature from 9th to the 16th  of January, both days inclusive, = $11.6 \times 8$ = 92.8°C

Similarly, Total Sum of all temperature from 10th to the 17th  of January = $12.2 \times 8$ = 97.6°C

Also, temperature on the 9th of January = 10.8°C

So, Temperature on the 17th of January = Temperature on the 9th of January + Total Sum of all temperature from 10th to the 17th  of January - Total Sum of all temperature from 9th to the 16th  of January

Temperature on the 17th of January = 10.8°C + 97.6°C - 92.8°C = 15.6°C