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    Question

    Dipti travels to her office at a speed of 45 km/h and

    returns at a speed of x km/h. If her average speed for the entire journey is 36 km/h, calculate the value of {x + 19}1/2 .
    A 7 Correct Answer Incorrect Answer
    B 12 Correct Answer Incorrect Answer
    C 5 Correct Answer Incorrect Answer
    D 8 Correct Answer Incorrect Answer
    E 10 Correct Answer Incorrect Answer

    Solution

    We know that, on covering same distance at two different speeds, s1 km/hr and s2 km/hr, respectively, then Average speed = (2 X s1 X s2) ÷ (s1 + s2) ATQ, 36 = (2 X 45 X x) ÷ (45 + x) 36 = 90x ÷ (45 + x) Or, 90x = 1620 + 36x Or, 54x = 1620 So, x = 1620/54 = 30 So, (x + 19) 1/2 = (49) 1/2 = 7

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