JEE Mains · Maths · STD 11 - 8. sequence and series
Let \(N\) be the sum of the numbers appeared when two fair dice are rolled and let the probability that \(N -2, \sqrt{3 N }, N +2\) are in geometric progression be \(\frac{ k }{48}\). Then the value of \(k\) is
- A \(2\)
- B \(4\)
- C \(16\)
- D \(8\)
Answer & Solution
Correct Answer
(B) \(4\)
Step-by-step Solution
Detailed explanation
\(n ( s )=36\) Given : \(N -2, \sqrt{3 N }, N +2\) are in G.P. \(3 N =( N -2)( N +2)\) \(3 N = N ^2-4\) \(\Rightarrow N ^2-3 N -4=0\) \(( N -4)( N +1)=0 \Rightarrow N =4 \text { or } N =-1 \text { rejected }\) \(( Sum =4) \equiv\{(1,3),(3,1),(2,2)\}\) \(n ( A )=3\)…
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