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Distance between A and B is 72 km. Two men started walking from A and B at the same time towards each other. The person who started from A traveled uniformly with average speed of 4 km/hr. The other man traveled with varying speed as follows: In the first hour his speed 2 km/hr, in the second hour it was 2.5 km/hr, in the third hour it was 3 km/hr, and so on. When / where will they meet each other?

A. 7 hours after starting

B. 10 hours after starting

C. 35 km from A

D. Mid-way between A and B

E. Can't be determined

Answer: Option D

Solution(By Examveda Team)

They covered the distance in this way together in different hours
6 + 6.5 + 7 + 7.5 + 8 + 8.5 + 9 + 9.5 + 10 = 72 Means,they'll meet at the 9th hr.
So, In that time A will cover = 4 × 9 = 36km
They will meet in Midway

This Question Belongs to Arithmetic Ability >> Percentage

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Comments ( 3 )

  1. Kumar Chandan
    Kumar Chandan :
    8 years ago

    Total distance = 72 km.
    Speed of A = 4 kmph.
    Speed of B = 2, 2.5, 3 and so on kmph.
    A and B are traveling in opposite direction. So,their relative speed would be,
    Relative speed = Speed of A + Speed of B.
    Speed of A is uniform while B has a varying speed.

    Relative Speeds,
    1st hour = 4 + 2 = 6 kmph.
    2nd hour = 4 + 2.5 = 6.5 kmph.
    3rd hour = 4 + 3 = 7 kmph.
    4th hour = 4 + 3.5 = 7.5 kmph.
    5th hour = 4 + 4 = 8 kmph.
    6th hour = 4 + 4.5 = 8.5 kmph.
    7th hour = 4 + 5 = 9 kmph.
    8th hour = 4 + 5.5 kmph.
    9th hour = 4 + 6 = 10 Kmph.

    In 9 hours, A and B together covered,
    6+6.5+7+7.5+8+8.5+9+9.5+10 = 72 Km.
    As 72 km is completed in 9 hour by both together, so they will meet of 9 hours.
    So, A will cover distance in 9 hours,
    = 9 *4 = 36 km.
    B also covered 36 km. Therefore, they meet at the mid point.

  2. Jyoti
    Jyoti :
    8 years ago

    how to come 9th hr

  3. Jyoti
    Jyoti :
    8 years ago

    6+6.5+7+7.5+....+10=72 how to come this plz Clearly Described

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