Let N be the sum of the numbers appeared when two fair dice are rolled and let the probability that are in geometric progression be . Then the value of k is
- (A)2
- (B)4✓ Correct
- (C)16
- (D)8
Answer: (B)
Solution
Three numbers are in geometric progression when the square of the middle equals the product of the extremes, so . This reduces to , that is . A sum of two dice lies between and , so the only admissible value is . The outcomes giving a sum of are , three of the equally likely results, so the probability is . Thus .
JEE Main · 2023 · 25 Jan 2023 · Shift 2 · Single correct option