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 = 36kmThey will meet in MidwayJoin The Discussion
Comments ( 3 )
Related Questions on Percentage
A. $$\frac{1}{4}$$
B. $$\frac{1}{3}$$
C. $$\frac{1}{2}$$
D. $$\frac{2}{3}$$
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.
how to come 9th hr
6+6.5+7+7.5+....+10=72 how to come this plz Clearly Described