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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 22 km, the find the total distance travelled by the bike in 12 hours.
    A 462 km Correct Answer Incorrect Answer
    B 422 km Correct Answer Incorrect Answer
    C 452 km Correct Answer Incorrect Answer
    D 432 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 = 22 km Distance travelled by the bike in 2nd hour = 22 + 3 = 25 km Distance travelled by the bike in 3rd hour = 25 + 3 = 28 km This form an AP i.e. 22, 25, 28………distance travelled in 12th hour Therefore, total distance travelled by the bike in 12 hours = sum of the AP Distance travelled in 12 hours = (n/2){2a + (n – 1)d} Where n = number of terms = 12, a = 1st term = 22 and d = common difference = 3 Therefore, distance travelled in 12 hours = (12/2){2 × 22 + (12 – 1) × 3} = (12/2)(44 + 33) = 462 km

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