The 50 companies’ percentages of revenues spent on R&D are repeated in Table 2.6. We have previously shown (see Figure 2.21) that the mean and standard deviation of these data (rounded) are 8.49 and 1.98, respectively. Calculate the fraction of these measurements that lie within the intervals x̄ ±  s, x̄ ± 2s, and x̄ ± 3s and compare the results with those predicted by Rules 2.1 and 2.2. 

Data from figure 2.21

Table 2.6 R&D Percentages for 50 Companies 13.5 7.2 9.7 11.3 8.0 9.5 7.1 7.5 5.6 7.4 8.2 9.0 7.2 10.1 10.5 6.5 9.9 5.9 8.0 7.8 8.4 8.2 6.6 8.5 7.9 8.1 13.2 11.1 11.7 6.5 6.9 9.2 8.8 7.1 6.9 7.5 6.9 5.2 7.7 6.5 10.5 9.6 10.6 9.4 6.8 13.5 7.7 8.2 6.0 9.5