Dopey Measurement

Stage: 3 Short Challenge Level: Challenge Level:2 Challenge Level:2

112.7 cm.

In order to calculate the mean height, Snow White had to first calculate the sum of the heights of the Dwarves ($S$), and then divide by 7. Her value for $S$ was too small by 3 cm, so her value for the mean was too small by $3/7 \approx 0.4$ cm. So the actual mean height is $112.3+0.4=112.7$ cm.

This problem is taken from the UKMT Mathematical Challenges.