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    Question

    The speed of a bike increases by 3 km/hr after every 1

    hour. If the distance travelled by the bike in 1st hour is 24 km, the find the total distance travelled by the bike in 10 hours.
    A 375 km Correct Answer Incorrect Answer
    B 365 km Correct Answer Incorrect Answer
    C 355 km Correct Answer Incorrect Answer
    D 345 km Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Since, the speed of the bike increases by 3 km/hr after every 1 hour, therefore the bike will travel 3 km extra after every 1 hour. Therefore, distance travelled by the bike in 1st hour = 24 km Distance travelled by the bike in 2nd hour = 24 + 3 = 27 km Distance travelled by the bike in 3rd hour = 27 + 3 = 30 km This form an AP i.e. 24, 27, 30………distance travelled in 16th hour Therefore, total distance travelled by the bike in 10 hours = sum of the AP Distance travelled in 10 hours = (n/2){2a + (n – 1)d} Where n = number of terms = 10, a = 1st term = 24 and d = common difference = 3 Therefore, distance travelled in 10 hours = (10/2){2 × 24 + (10 – 1) × 3} = (10/2)(48 + 27) = 375 km

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