Correct answer: (A) E[1/(X+1)]>0.1 and P(X≥10)≤0.9
Explanation
The function 1/(x+1) is strictly convex for positive x. Strict Jensen gives E[1/(X+1)]>1/(E X+1)=.1 because X is nonconstant. Markov’s inequality gives P(X≥10)≤E X/10=.9. **A**.
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