एक उचित सिक्के को उछाले जाने पर, चित के आने की संख्या मान लीजिए X है, यदि P(x = 4), P(x = 5) और P(x = 6) AP में हैं, तो n का मान ज्ञात करें।

  1. 7
  2. 10
  3. 12
  4. 15

Answer (Detailed Solution Below)

Option 1 : 7
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Detailed Solution

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स्पष्ट रूप से, एक्स एक द्विपदीय चर है और n और p = 1/2 इसके प्राचल हैं, इस प्रकार कि,

अब, P (x = 4), P(x = 5) और P(x = 6) AP में हैं।

यदि a, b, c AP में हैं तो 2b = a+c

∴ 2P (x = 5) = P (x = 4) + P (x = 6)

⇒ 2.nC5 = nC4 + nC6

⇒ n2 – 21n + 98 = 0 ⇒ (n – 7) (n – 14) = 0

∴ n = 7 or 14

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