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    Question

    A train would take 45 seconds to cross a

    standing man. If the train was 100m longer, it would have taken 20 seconds more. Find the speed of the train.
    A 5 m/sec Correct Answer Incorrect Answer
    B 9m/sec Correct Answer Incorrect Answer
    C 15 m/sec Correct Answer Incorrect Answer
    D 10 m/sec Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    let the original length of the train = x m ∴ Speed of the original train = [if gte msEquation 12]> x 45 [if !msEquation]--> [endif]-->`x/45` m/s ∴ Length of the longer train =`x+100` [if gte msEquation 12]>x+100 [if !msEquation]--> [endif]--> ∴ speed of the longer train = [if gte msEquation 12]> x+100 65 [if !msEquation]--> [endif]-->`(x+100)/65` m/s Since, both the train are same their speed are also same ∴ [if gte msEquation 12]> x 45 [if !msEquation]--> [endif]-->`x/45` =`(x+100)/65` [if gte msEquation 12]> x + 100 65 [if !msEquation]--> [endif]--> ⟹ 65 x = 45x [if gte msEquation 12]> x [if !msEquation]--> [endif]-->+ 4,500 ⟹ 20 x = 4,500 ⟹ [if gte msEquation 12]>x [if !msEquation]--> x = 225 ∴ Speed = `x/45` [if gte msEquation 12]> x 45 [if !msEquation]--> [endif]-->=`225/45` [if gte msEquation 12]> 225 45 [if !msEquation]--> [endif]-->= 5m/s

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