Latest Elitmus Aptitude Question SOLUTION: Einstein walks on an escalator at a rate of 5steps per second and reaches the other end in 10 sec. while coming back, walking at the same speed he reaches the starting point in 40s

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(#M40154332) ELITMUS Numerical Ability question time speed & distance Keep an EYE

Einstein walks on an escalator at a rate of 5steps per second and reaches the other end in 10 sec. while coming back, walking at the same speed he reaches the starting point in 40secs. What is the number of steps on the escalator?

a)40 b)60 c)120 d)80 e)data insufficient

Asked In Elitmus vani.plmr@gmail.com (8 years ago)

Unsolved Read Solution (9)

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Read Solution (9) :

Rahul Tiwari  (8 years ago)

Let the speed of escaltor be X steps per sec.
And length of escalator be Y.
Einstein's speed = 5 step/ sec

Then,
During upward movement
5-X=Y/10

During downward movement
5+X=Y/40

By solving equations we get Y=80.

Is this solution Helpfull? Yes (34) | No (6)  

mukesh kumar mishra  (8 years ago)

Correct it if I am wrong....

Here whatever the speed, Distance is constant...

This is based on boat and stream type.

solution:-

speed of moving = 5 steps/ sec
Time taken = 10 sec

clearly in question given that it takes less time in going than returning.

Return time = 40 sec

lets speed of escalator = y steps / sec

so, distance= speed X time
speed of moving forward = (5 + y) steps / sec
speed of moving returning = (5 - y) steps / sec

Hence , (5+y) X 10 = ( 5 - y) X 40
=> (5+y) X 1 = ( 5 - y) X 4
=> 5 +y = 20 - 4y
=> y + 4y = 20 - 5
=> 5y = 15
ie.. y = 3

now total speed of moving with escalor = 5 + 3 = 8 steps /sec

Total steps = distance
= 8 *10;
= 80 STEPS

so D is right ans

Is this solution Helpfull? Yes (28) | No   

Pintu kumar  (8 years ago)

let speed of escalator is x steps per second.
when einstein walks same direction of escalator then his speed will be (5+x) steps per second.
when einstein walks opposite direction of escalator then his speed will be (5-x) steps per second.

so,
10*(5+x)=40*(5-x)
=> x=3
number of steps=10*5+10*3=80
ans is option (d ) 80

Is this solution Helpfull? Yes (7) | No   

shankar sahu  (8 years ago)

let einstein speed be S and escalator speed be s..
then,a/c to question
and no. of steps be the distance travelled by einstien is x so..
(S+s)*10=x
(S-s)*40=x
then equate both equation,
we the value of s(speed of escalator)=3
speed of einstien is given as 5
so put both value in any equation..
ans-80.

Is this solution Helpfull? Yes (5) | No   

sarfarosh khan  (8 years ago)

let the total step be T
and escalator speed be S
T/(S+5)=10
S=T-50/10
then from second data
T/(S-5)=40
now putting value of S
T=40(T-50)/10 - 200
3T=400
T=133.33
is the answer

Is this solution Helpfull? Yes (3) | No (8)  

Shailaja Sharma  (8 years ago)

5=t/10 +t/40
5=5t/40
t=40

ans) a

Is this solution Helpfull? Yes (1) | No (7)  

sivasai reddy  (6 years ago)

Average age of 11 players at present= x(let), then

Sum of their ages= 11x ⇔ Sum of their ages 3 years back= 11x - 33

Sum of current age of 3 outgoing players= 3×33= 99

Sum of their current age after deducting ages of 3 outgoing players= 11x-99

Let, sum of ages of 3 newcomers = N

Now, new sum = 11x - 99 + N

As per question,

11x - 33 = 11x - 99 + N

⇒ N = 66

∴ Average of 3 newcomers = N/3 = 66/3 = 22

Is this solution Helpfull? Yes (1) | No   

Arush Anand  (8 years ago)

Data insufficient

Is this solution Helpfull? Yes | No (11)  

Gourav Khandelwal  (8 years ago)

data insufficient becoz there is nothing to be said about the escalator.

Is this solution Helpfull? Yes | No (12)  

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