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Two integers x and y are chosen with replacement from the set \0, 1, 2, 3, dots, 10\. Then the probability that |x - y| > 5 is:

Solution & Explanation

### Related Formula P(E) = fractextNumber of favorable outcomestextTotal number of possible outcomes ### Core Logic Total possible selections for (x, y) with replacement from 0, 1, dots, 10 is 11 times 11 = 121. We need pairs (x, y) such that |x - y| > 5, which means x - y > 5 or y - x > 5. ### Step 1: Counting Favorable Cases Assume x < y, so we need y - x geq 6. If x = 0 Rightarrow y in \6, 7, 8, 9, 10\ (5 ways) If x = 1 Rightarrow y in \7, 8, 9, 10\ (4 ways) If x = 2 Rightarrow y in \8, 9, 10\ (3 ways) If x = 3 Rightarrow y in \9, 10\ (2 ways) If x = 4 Rightarrow y in \10\ (1 way) If x ge 5, there are no possible values for y strictly greater than x satisfying the condition. ### Step 2: Total Probability The number of cases for y > x is 5 + 4 + 3 + 2 + 1 = 15. By symmetry, the number of cases for x > y is also 15. Total favorable cases = 15 times 2 = 30. Required probability = frac30121. ### Pattern Recognition Absolute difference conditions |x - y| > k on discrete sets cleanly split into symmetric additive series 1+2+...+n. Calculate one half and multiply by 2. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Probability

Reference Study Guides

More Probability Previous-Year Questions — Page 6

Q19 jee_main_2024_31_jan_morning Variance of Random Variable
Three rotten apples are accidently mixed with fifteen good apples. Assuming the random variable X to be the number of rotten apples in a draw of two apples, the variance of X is
  • A. frac37153
  • B. frac57153
  • C. frac47153
  • D. frac40153

Solution

### Core Logic Total apples = 18 (3 rotten, 15 good). Random variable X = \0, 1, 2\ representing the number of rotten apples. ### Step 1: Probability Distribution P(X = 0) = frac^15C_2^18C_2 = frac105153 P(X = 1) = frac^3C_1 times ^15C_1^18C_2 = frac45153 P(X = 2) = frac^3C_2^18C_2 = frac3153 ### Step 2: Expectation E(X) = 0 times frac105153 + 1 times frac45153 + 2 times frac3153 = frac51153 = frac13 ### Step 3: Variance E(X^2) = 0 times frac105153 + 1 times frac45153 + 4 times frac3153 = frac57153 Var(X) = E(X^2) - (E(X))^2 = frac57153 - left(frac13right)^2 = frac57153 - frac17153 = frac40153 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Probability

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