Question:
A child’s game has 8 triangles of which 3 are blue and rest are red, and 10 squares of which 6 are blue and rest are red. One piece is lost at random.
Find the probability that it is a
(i) triangle
(ii) square
(iii)square of blue colour
(iv) triangle of red colour
Solution:
Total number of figures
$n(S)=8$ triangles $+10$ squares $=18$
(i) $P$ (lost piece is a triangle) $=\frac{8}{18}=\frac{4}{9}$
(ii) $P$ (lost piece is a square) $=\frac{10}{18}=\frac{5}{9}$
(iii) $P$ (square of blue colour) $=\frac{6}{18}=\frac{1}{3}$
(iv) $P$ (triangle of red colour) $=\frac{5}{18}$