Question

In a Carton, there were blue, red, green and yellow balls. There were 240 balls. The number of balls of each colour is represented in the following pie chart. If Shreya picked a ball at random, then what is the probability that she picked a yellow ball ? If 20 more yellow balls were added to the carton, what is the probability that now she picked a ball which is yellow or green ?

Accepted Answer

Initial yellow probability = $\frac{30^\circ}{360^\circ} = \frac{1}{12}$. Initial yellow balls = $\frac{1}{12} 	imes 240 = 20$. Green balls = $\frac{90^\circ}{360^\circ} 	imes 240 = 60$. When 20 yellow balls are added: total balls = $240 + 20 = 260$. New yellow balls = $20 + 20 = 40$. Yellow or green balls = $40 + 60 = 100$. New probability = $\frac{100}{260} = \frac{5}{13}$.

Probability from pie chart of balls

Explanation

Practise this under board exam conditions