n(S) = 2³ = 8
Let E = Event of getting exactly two heads
= {(H, H, T), (H, T ,H), (T, H, H)}

Correct Option: C

n(S) = 2³ = 8
Let E = Event of getting exactly two heads
= {(H, H, T), (H, T ,H), (T, H, H)}
⇒ n(E) = 3
∴ required probability = 3/8

n(S) = 49
Favourable numbers are 11, 21, 31, 41.

Correct Option: B

n(S) = 49
Favourable numbers are 11, 21, 31, 41.
∴ Required probability = 4/49

n(s) = 50
Prime numbers are = 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47
∴ n(E) = 15

Correct Option: C

n(s) = 50
Prime numbers are = 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47
∴ n(E) = 15
∴ p(E) = 15/50 = 3/10 = 0.3

Required probability = (²C₁ x ³C₂ + ²C₂ x ³C₁) / (⁵C₃)

Correct Option: C

Required probability = (²C₁ x ³C₂ + ²C₂ x ³C₁) / (⁵C₃) = 9/10

Number of ways to select 3 marbles out of 7 marbles = n(s) = ⁷C₃ = 35
Probability that 2 are green and 1 is red = n(E) = ⁴C₂ x ³C₁ = 18

Correct Option: B

Number of ways to select 3 marbles out of 7 marbles = n(s) = ⁷C₃ = 35
Probability that 2 are green and 1 is red = n(E) = ⁴C₂ x ³C₁ = 18
∴ Required probability = 18/35