Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationnPr & nCrMedium2 minQB

MathematicsMediumsingle choice

The no.of rational numbers lying in the interval $(2002, 2003)$ all whose digits after the decimal point are non-zero and are in decreasing order

Answer:

Solution:

A rational number of the desired category is of the form 2002.

$x_{1} x_{2} \dots x_{K} (1 \leq K \leq 9$ and $9 \geq x_{1} > x_{2} > \dots > x_{K} \geq 1)$

total $=^{9} C_{1} +^{9} C_{2} + \dots\dots +^{9} C_{9} = 2^{9} - 1$

Stream:JEESubject:MathematicsTopic:Permutation & CombinationSubtopic:nPr & nCr

⏱ 2mℹ️ Source: QB

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