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8th Class Mathematics Factorisation Question Bank Factors & Multiples

  • question_answer
    Four prime numbers are in ascending order of their magnitudes. The product of the first three is 2, 431 and that of the last three is 4, 199. The largest given prime number is

    A)  11

    B)  13

    C)  17

    D)  19

    Correct Answer: D

    Solution :

    Let the number be a, b, c and d Given that \[a\times b\times c=2,431\]       .............(i) and      \[b\times c\times d=4,199\]      .............(ii) Now, divide equation (ii) by equation (i) \[\frac{b\times c\times d}{a\times b\times c}=\frac{4,199}{2431}\]\[\Rightarrow \frac{d}{a}=\frac{4,199}{2431}=\frac{13\times 17\times 19}{11\times 13\times 17}=\frac{d}{a}=\frac{19}{11}\] Hence, the largest number is 19.


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