Different sports played by the students of a school in

SOLUTION

The height of each bar gives the number of students who played particular sports.
Total number of students who played in 2019 = sum of length of all blue bars
        = 10 + 10 + 10 + 15 =  45
Total number of students played in 2018 = sum of length of all red bars
         = 5 + 15 + 20 + 10 =  50
$\therefore$ the required ratio $=\frac{45}{50}$ =  $\frac{9}{10}=0.9$