(1) According to the bar chart, we can get the following results: the number of people participating in basketball activities is175;

(2) 175÷35%=500;

(3) If the understanding of skipping is X, then the number of people participating in badminton is x+75, which means 175+x+(x+75)=500.

Solution: x = 125.

Then the number of people who take part in skipping rope is 125500× 360 = 90, and the ratio is 125500× 100% = 25%.