Assuming that they are all girls, * * * has 70× 100=7000 (points), which is 7000-6300=700 (points) more than the actual situation.

On average, each boy is 70-60= 10 (points) less than each girl. If * * * is 700 points more, there are 700 boys, and 10 = 70 girls.

Extended data:

In statistical work, mean and standard deviation are the two most important measures to describe the trend and deviation of data sets. Statistical average is used to reflect the overall level of the overall phenomenon, or the centralized trend of distribution. Calculate the digital average by comparing the total number of marks with the total number of units.

It is intuitive and concise to represent a set of data by average, so it is often used in daily life, such as average speed, average height, average yield, average score and so on.