Answer: Probability of getting a blue side will be

Explanation:
Since we have given that
Number of times she tossed the stone = 200
Number of times it lands on red side = 150
Probability of getting a red side is given by

Probability of getting a blue side will be

According to question, she tossed the stone 20 more times i.e.

We have to find the number of times the stone will land blue side up :
As we know that number of chances of getting a blue side is

So, Number of times the stone will land blue side up will be same for next 20 times.