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since the two robots start from the diametrically opposite points of a circular track in opposite directions.
time for the second meet??
1.time for the first meet is 26 seconds.
no information about the length of the track or the speeds of the robots --INSUFFICIENT
2. given s1:s2=3:4 where s1 and s2 are speeds of the two robots
still no information about the length of the track---INSUFFICIENT
together also we have no information about the length of the track as well the actual speeds of the robots so together INSUFFICIENT
E
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Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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let radius = r
speeds be - v1 & v2
relative speed = v1+v2= v (say)
time to meet first time=pi r/v =t (say)
time to meet 2nd time = t+ 2 pi r/v= t + 2t=3t
stmnt1--- t= 26 sec - sufficient
stmnt2-- v1/v2=3/4--- insufficient
Ans- A
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the full diameter is D so half is D/2. currently they are D/2 distance apart from each other.
wen need to find time taken to meet for the second time.

s-1
meeting first time after 26 second. now they have to take full circle back to meet again.
so for half they took 26 so for full they have to take double of that which is 52.
so its sufficient.

s-2 it talks about speed ,but we dont anything about time or distance at all.
not sufficient.

A is ans

Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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Statement 1: only time is given.
insufficient

Statement 2: only speed ratio is given
insufficient.

Combined:
v1: v2 = 3/4

So it time is constant, their distance covered d1: d2 = 3:4
meaning, they cover 3/7 th of distance and 4/7th of distance respectively in a given time.

we know than in 26 seconds, they both went towards each other in half circle.
Let circumference be T.

in 26 seconds, first one covered, 3/7th of T/2 distance
second one covered, 4/7th of T/2 distance

Once they meet, they have to cover together a total of T (circumference) distance.
In that, first one covers 3/7th of T. We know to cover 3/7th of T/2, it took 26 seconds.
Then, to cover 3/7th of T, it takes 52 seconds.
sufficient

Ans: Option C
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Quote:
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

The two robots are diametrically opposite each other, meaning their distance is 1/2 of the circumference (C) of this corridior.
As they move in opposite direction, the distance they covered when they first met is exactly 1/2 C. To meet the second time, they have to travel a combined distance that is the length of the circumference itself. Thus, the distance they have travelled right before meeting the second time is 1/2C + C = 3/2 C
(1) this means to travel 1/2C, it took them 26 seconds. Since their speeds are constant, it will take them 26*3 = 78 seconds to travel 3/2C to meet the second time. This is sufficient.
(2) This tells us the speed ratio of the two robots. However, without the length or the time it takes them to travel, this does not tell us neither the first nor the second time they met. This is insufficient.
The answer is A
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Say the circumference of the circle is A.
When they meet for the first time, they have moved half of the circle.
=> T1 = 0.5A/(v1+v2) (v1 and v2 is the speed of two robots respectively)

And when they meet for the second time, they have moved addtionally a circle.
=> T2 = A/(v1+v2)

(1) T1 = 26s => T2 = 2T1 = 52s. SUFFICIENT

(2) v1 = 3/4 * v2. We need to have information about T and A to solve T2. NOT SUFFICIENT.

Answer: A.
Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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The corridor is circular
The robot starts half a circle apart
Let circumference = C
Speeds: V1 & V2
Relative speed: V1 + V2
First meeting : (C/2) / (V1+V2)
Second meeting at full circler: (3C/2) / (V1+V2)
Second meeting = 3 x First meeting
(1) They meet for the first time 26 seconds after they start
Second meeting - 3 * 26 = 78 seconds

(2) One robot movies at a speed that is 3/4 the speed of the other
This gives only a speed ratio , not actual distance
Statement (2) not sufficient

Ans choice (A)
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Given that both are starting at the same time from points diametrically , opposite each other , and one is moving clockwise and another one anticlockwise , Let's speed of one robot be s1 , another be s2 , first meeting time be t1 , second meeting time after first meet be t2. We need to find the value of t1+t2.

Applying relative speed concept , s1+s2=d/t1 , s1+s2 = 2d/t2 , in second equation it's 2d because we first assumed the initial seperation distance is d. Then total circular distance will be 2d.

So , d/t1 = 2d/t2

t2 = 2t1

so , t1+t2 = 3t1

Let's check first statement ,

I. t1 is given as 26 seconds , which is sufficient to find 3t1 which is 78 seconds. So After the start they meet second after 78 seconds.

II. Let S1 = 3/4 S2 , then 7/4 S2 = d/t1 , so t1 = (4/7) (d/S2) , 3t1 = 12/7 * (d/S2). So It's value depends on d which was initial separating distance and any one speed of Robot. So this statement is insufficient.

So , A is the answer.
Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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statement 1: the robots start diametrically opposite, so they cover half the circumference in 26s, for the next time they meet they should cover the entire circumference. This statement is sufficient.

statement 2: one robots speed is given in terms of the other. Not sufficient.

Ans: A
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Let the circumference of the circle be d and speeds of the robots be an and b. The time taken for their first meet, since they are travelling in opposite directions and have to cover d/2 distance is d/2(a+b). From this point, they are still in travelling in opposite directions and now have to cover the entire portion d. So the questions asks for the value of d/(a+b)

Statement 1 - d/2(a+b) = 26. From this, we can find d/(a+b). Therefore, sufficient

Statement 2- we are only given a in term of b. We still do not know the value of d and the value of one of the speeds a or b. Not sufficient.


Therefore, Option A
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First time meeting distance = C/2=(v1+v2)*t1
Second time distance complete circle C = 2*(v1+v2)*t1
t2=C/(v1+v2) = 2(v1+v2)*t1/(v1+v2) = 2t1.
Total time for meeting second time will be t1+2t1 = 3t1.
Statement I - t1 =26 seconds
3t1 = 78 seconds sufficient to answer the question.
Statement - Talking about speeds. Nothing mentioned about time. (not sufficient)
Answer A.
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Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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Let c be the perimeter of circle.

let v1 be speed of first robot
let v2 be speed of second robot

Now, time for first meet would be

total distance = c/2 (as they cover c/2 distance together)
total relative speed = v1 - (-v2) = v1 + v2

time, t1 = (c/2)/(v1+v2)

and they'll meet next after covering one more revolution, distance c

time for second meet, t2 = (c+c/2)(v1+v2) = 3 (c/2)/(v1+v2)

So if we know t1, we know t2

or if we know all c, v1, v2 we know t2

(1) They meet for the first time 26 seconds after they start.
We know t1, Sufficient AD/BCE

(2) One robot moves at a speed that is 3/4 the speed of the other.
Without knowing v1, v2, c it's not possible to calculate t2 or t1.
Insufficient AD/BCE

Correct Answer: A
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Two Robots start at diametrically opposite points on a circle . This means the distance between them is exactly half the circumference (C/2).
St 1 : They meet for the first time 26 sec after they start.
To meet for second time they must cover an additional full circumference (C) From their first meeting point .
If it took 26 sec to cover C/2 , it will be exactly double the time .
Total Time = 26 (First Meeting ) + 52 (additional time )= 78 secs . Sufficient.

ST 2 : Gives ratio of speed but no actual distance of time or distance. Not Sufficient.
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Let D be the total distance between two robots. So total circular track length= 2D
They are moving towards each other so they will cover distance D.
Statement 1
They take 26 seconds to meet first time.
So distance travelled is D and time is 26 seconds and have speed V1 & V2 which is constant, 26=D/(v1+V2)
For 2nd meeting they will cover 2D and speed=v1+v2, time= 2D/(v1+v2)= 2*26=52

Statement 2
V2=3/4V1 so t=D/4/3v1, D & V1 not known Multiple ans possible.
Statement 2 not sufficient.

Answer is A.
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Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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Both robots moving in opposite direction at constant speed

So when the robot will meet the first time, they would cover half the distance together and consequently, when they meet the second time they will cover full length of the circle together

when two robots meet for first time :

(V1 + v2 ) * t = D/2 { V1,v2 are the speed for both robots, D is the Distance, t1 is time)

t1 = D/(2 * V) { V1 + v2 = V} ---- 1

When two robots meet for second time :

V * t = D
t2 = D/V ----- 2

compare 1 & 2

t2 is double of t1

let's move to statement now

Statement 1 : it give us the time taken, when they meet first time

so as we know : t2 = 2t1

t2 = 52 seconds

So Statement 1 is sufficient

Statement 2 : we can't deduce anything from this statement

Statement 2 is not enough

So our answer is A
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Given: circular room - diagonally opposite - running towards each other.
time to meet 2nd time = [distance b/w them]/[v1 + v2]

A -> 1st time meet = 26 seconds -> second time will be twice the time since post 1st time meeting they will be at the same point and have to cover full circle to meet = 52 sec -> yes

B -> v1 = 3v2/4 - does not tell about distance and absolute velocity hence -> not sufficient.

Ans - A alone
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Bunuel
Two autonomous cleaning robots move along a long circular corridor. They start at the same time from points diametrically opposite each other on the corridor, one moving clockwise and the other moving counterclockwise. They continue without stopping at their own constant speeds. After how many seconds after they start do they meet for the second time?

(1) They meet for the first time 26 seconds after they start.
(2) One robot moves at a speed that is 3/4 the speed of the other.

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Perimeter of the circle = 2*pi*r

Statement 1:

When the robots meet for the first time, they would have covered pi * r distance jointly.

26s1 + 26s2 = pi * R

s1+ s2 = (pi * R) /26

When they meet for the second time, the robots would have covered one full circle

2 * pi * r + pi * r = 3 * pi * r

Let's say they meet at time t2

s1 * t2 + s2 * t2 = 3 * pi * r

t2(s1+s2) = 3 * pi * r

Substituting the value of s1+s2

t2 = 3 * 26 = 78

Statement 2

Robot 1 = s
Robot 2 = 0.75s

This information is not sufficient to find the time as we don't know the value of s or R.

Option A
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