What is the greatest value of r satisfying the inequality \( ^{15}C_{r+1} > 2 \times {^{15}C_r} \) ?

  1. A. 2
  2. B. 3
  3. C. 4
  4. D. 5

Correct Answer: C. 4

Explanation

Expanding the binomial coefficients gives the condition 15 - r > 2(r + 1), which simplifies to 3r < 13. The greatest integer value is 4.

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