If X ~ B n , p with n = 10 , p = 0.4 then E X 2 =

Question

If X ~ B n , p with n = 10 , p = 0.4 then E X 2 =, 4, 2.4, 3.6, 18.4

MARKS App · Accepted Answer

Given X ∼ B ( n , p ) ; n = 10 , p = 0.4 ⇒ q = 0.6 We know that V ( X ) = n p q E ( X ) = n p ⇒ V ( X ) = 10 × 0.4 × 0.6 = 2.4 E ( X ) = 10 × 0.4 = 4 Also V ( X ) = E ( X 2 ) − ( E ( X ) ) 2 ⇒ 2.4 + 4 2 = E ( X 2 ) ⇒ E ( X 2 ) = 18.4

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