JEE Main & Advanced JEE Main Paper Phase-I (Held on 08-1-2020 Morning)

  • question_answer
    If a, b and c are the greatest values of \[^{19}{{C}_{p}}{{,}^{20}}{{C}_{q}}\] and \[^{21}{{C}_{r}}\] respectively, then [JEE MAIN Held On 08-01-2020 Morning]

    A) \[\frac{a}{10}=\frac{b}{11}=\frac{c}{42}\]

    B) \[\frac{a}{11}=\frac{b}{22}=\frac{c}{42}\]

    C) \[\frac{a}{10}=\frac{b}{11}=\frac{c}{21}\]

    D) \[\frac{a}{11}=\frac{b}{22}=\frac{c}{21}\]

    Correct Answer: B

    Solution :

    [b] \[a={}^{19}{{C}_{10}}\,\,\text{or}\,{{\,}^{19}}{{C}_{19}}\] \[b={}^{20}{{C}_{10}}\] \[c={}^{21}{{C}_{10}}\,\text{or}{{\,}^{21}}{{C}_{11}}\] \[\Rightarrow 1=\frac{a}{^{19}{{C}_{10}}}=\frac{b}{^{20}{{C}_{10}}}=\frac{c}{^{21}{{C}_{10}}}\] \[\Rightarrow \frac{a}{11}=\frac{b}{22}=\frac{c}{42}\]


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