JEE Mains · Maths · STD 11 - 14. probability
Let \(A\) be a set of all \(4 -\)digit natural numbers whose exactly one digit is \(7 .\) Then the probability that a randomly chosen element of \(A\) leaves remainder \(2\) when divided by \(5\) is ..... .
- A \(\frac{2}{9}\)
- B \(\frac{122}{297}\)
- C \(\frac{97}{297}\)
- D \(\frac{1}{5}\)
Answer & Solution
Correct Answer
(C) \(\frac{97}{297}\)
Step-by-step Solution
Detailed explanation
\(n ( s )= n (\) when 7 appears on thousands place) \(+ n (7\) does not appear on thousands place) \(=9 \times 9 \times 9+8 \times 9 \times 9 \times 3\) \(=33 \times 9 \times 9\) \(n ( E ) = n (\text { last digit } 7 \& 7 \text { appears once })\) \(+ n (\) last digit 2 when 7…
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