CTET 2 Math and Science Jul 2019 Paper

Total sample space to draw a ball ${=}^{10}{\mathit{C}}_1=10$
Favourable case = Draw a Red ball from 5 Red balls ${=}^5{\mathit{C}}_1=5$
∴ Probability that the ball drawn is red $=\frac{5}{10}=\frac{1}{2}$
Then,
Required probability that the ball drawn is not red $=1-\frac{1}{2}=\frac{1}{2}$