The bar graph shows the data of the students who appeared and passed in an examination for four school P, Q, R and S. The average of success rates (in percentage) of these four schools is _____.

The correct option is 59.0%.

Based on the provided bar graph "Performance of School P, Q, R and S", we can extract the number of students who appeared and passed from each school:
1. School P:
Number of students appeared = 500
Number of students passed = 280
2. School Q:
Number of students appeared = 600
Number of students passed = 330
3. School R:
Number of students appeared = 700
Number of students passed = 455
4. School S:
Number of students appeared = 400
Number of students passed = 240

Now, we calculate the success rate (in percentage) for each school using the formula:
$$\text{Success Rate}=\left(\frac{\text{Number of Students Passed}}{\text{Number of Students Appeared}}\right)\times 100$$

Success Rate of School P:
$$\text{Success Rate}\left(\text{P}\right)=\frac{280}{500}\times 100=56\%$$

Success Rate of School Q:
$$\text{Success Rate}\left(\text{Q}\right)=\frac{330}{600}\times 100=55\%$$

Success Rate of School R:
$$\text{Success Rate}\left(\text{R}\right)=\frac{455}{700}\times 100=65\%$$

Success Rate of School S:
$$\text{Success Rate}\left(\text{S}\right)=\frac{240}{400}\times 100=60\%$$

To find the average of success rates of these four schools, we sum up the individual success rates and divide by the number of schools (4):
$$\text{Average Success Rate}=\frac{56+55+65+60}{4}$$
$$\text{Average Success Rate}=\frac{236}{4}=59.0\%$$