Average temperature of a week is 30°C. If the average of first 4 days was 31°C, then average temperature of the remaining days will be:

Answer: Option D

Total temperature of the week = 30°C × 7 = 210°C
Total temperature first four day = 31°C × 4 = 124°C
Average temperature of remaining day
$$\begin{array}{rl}& =\frac{{210}^{\circ }\text{C}-{124}^{\circ }\text{C}}{3}\\ & =\frac{{86}^{\circ }\text{C}}{3}\\ & =28.67^{\circ }\text{C}\end{array}$$