CLAT Sample Paper CLAT Sample Paper-8

  • question_answer
    The first and the last term of an arithmetic progression are 4 and 128, respectively. If the sum of all the terms is 2970, what is the number of terms?

    A)  40                               

    B)  45

    C)  51                   

    D)         Cannot be determined

    Correct Answer: B

    Solution :

    We know that, sum of terms of an AP series \[\text{=}\,\,\left[ \frac{\text{First}\,\text{term}\,=\text{Last}\,\text{term}}{\text{2}} \right]\,\,\text{ }\!\!\times\!\!\text{ }\,\text{Number}\,\text{of}\,\text{terms}\] \[=2950\] \[\Rightarrow \]   \[\left( \frac{4+128}{2} \right)\times \,n=2970\] \[\therefore \]      \[n=45\]

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