Answer:
Option 4 is correct. The length of PR is 6.4 units.
Step-by-step explanation:
From the given figure it is noticed that the triangle PQR and triangle MQR.
Let the length of PR be x.
Pythagoras formula

Use pythagoras formula for triangle PQM.





The value of PM is 10. The length of PR is x, so the length of MR is (10-x).
Use pythagoras formula for triangle PQR.


.....(1)
Use pythagoras formula for triangle MQR.



.... (2)
From equation (1) and (2) we get




Therefore length of PR is 6.4 units and option 4 is correct.

Perimeter of given figure is equal to :
Perimeter of square - side length + quarter Circumference of the circle
that is :





So, the required perimeter is 37.85 units
10 + 20 = 30 total balls.
Picking red = 10/30 = 1/3
After picking one ball there are 29 balls left.
Picking a yellow next is 20/29
Then there are 28 balls left and 19 yellow left, so picking another yellow would be 19/28
The probability of picking red first then two yellow = 1/3 x 20/29 x 19/28 = 95/609