- Keith records the amount of rainfall, in mm , at his school, each day for a week. The results are given below.
0.0
0.5
1.8
2.8
2.3
5.6
9.4
Jenny then records the amount of rainfall, \(x \mathrm {~mm}\), at the school each day for the following 21 days. The results for the 21 days are summarised below.
$$\sum x = 84.6$$
- Calculate the mean amount of rainfall during the whole 28 days.
Keith realises that he has transposed two of his figures. The number 9.4 should have been 4.9 and the number 0.5 should have been 5.0
Keith corrects these figures.
- State, giving your reason, the effect this will have on the mean.