There is a square board of side '2a' units circumscribing a red  circle. Jayadev  asked to keep a dot on the above said board. The probability that he keeps the dot on the shaded region is. 

(a) π/4   (b) (4-π)/4   (c) (π - 4)/4    (d) 4/π

There is a square board of side ‘2a’ units circumscribing a red circle - CBSE Class 10 Sample Paper for 2024 Boards - Maths Standard

part 2 - Question 16 - CBSE Class 10 Sample Paper for 2024 Boards - Maths Standard - Solutions of Sample Papers for Class 10 Boards - Class 10
part 3 - Question 16 - CBSE Class 10 Sample Paper for 2024 Boards - Maths Standard - Solutions of Sample Papers for Class 10 Boards - Class 10

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Transcript

Probability of placing a dot on shaded region = (𝐴𝑟𝑒𝑎 𝑜𝑓 𝑠ℎ𝑎𝑑𝑒𝑑 𝑟𝑒𝑔𝑖𝑜𝑛 (𝑏𝑙𝑢𝑒))/(𝑇𝑜𝑡𝑎𝑙 𝑎𝑟𝑒𝑎) = (𝑨𝒓𝒆𝒂 𝒐𝒇 𝒔𝒒𝒖𝒂𝒓𝒆 − 𝑨𝒓𝒆𝒂 𝒐𝒇 𝒄𝒊𝒓𝒄𝒍𝒆)/(𝑨𝒓𝒆𝒂 𝒐𝒇 𝒄𝒊𝒓𝒄𝒍𝒆) Area of square Side = 2a Area = 〖(2𝑎)〗^2 =〖 𝟒𝒂〗^𝟐 units Area of circle Radius of circle = 2𝑎/2 = a Area of circle = π𝑎^2 Now, Probability of placing a dot on shaded region = (𝑨𝒓𝒆𝒂 𝒐𝒇 𝒔𝒒𝒖𝒂𝒓𝒆 − 𝑨𝒓𝒆𝒂 𝒐𝒇 𝒄𝒊𝒓𝒄𝒍𝒆)/(𝑨𝒓𝒆𝒂 𝒐𝒇 𝒄𝒊𝒓𝒄𝒍𝒆) = (4𝑎^2−𝜋𝑎^2)/(4𝑎^2 ) = ((4 − 𝜋 ) 𝑎^2)/〖 4𝑎〗^2 = (4 − 𝜋)/4So, the correct answer is (b)

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