Time speed, work, Alligations and mixtures problems

jain12345

hi guys there were some questions asked on escalators in CAT...
so can anybody post some question on escalator so it will be helpful for all of us...
or can anybody help that is there any separate thread for it...

cheers

prakharc

Q1)An escalator is descending at constant speed. A walks down and takes 50 steps to reach the bottom. B runs down and takes 90 steps in the same time as A takes 10 steps. How many steps are visible when the escalator is not operating?

Q2)An upward moving-escalator
Ram moving down counted steps--150
Sham moving up counted steps--75
Ram covers 3 times steps as sham in a given time.
Wats the No. of steps on the escalators?

msksent

The answer will be 100 steps

msksent

The answer for the second problem will be 300 steps

sharulgoel

If a man travels 3 distances that are in AP with speeds that are in GP such that the middle term of the AP is equal to the middle term of GP and the common difference of the AP is equal to the common ratio of the GP, then find the average speed for the entire journey given that he took 72 mins for the first part of the journey and 42 min for the last part of the journey.

srikar2097

Quote:

Originally Posted by sharulgoel

If a man travels 3 distances that are in AP with speeds that are in GP such that the middle term of the AP is equal to the middle term of GP and the common difference of the AP is equal to the common ratio of the GP, then find the average speed for the entire journey given that he took 72 mins for the first part of the journey and 42 min for the last part of the journey.

A weird attempt, didn't get the answer but...

Let the distances be = (a-d), a, (a+d)
and the speeds be = (a/d), a, (ad)

=> (a-d) = (a/d) * 72 ---->1
and (a+d) = (ad) * 42 ---->2

solving (1) and (2) we get 1 = (36/d) + (21d)
or 21d^2 - d + 36 = 0
but this gives complex roots

Am I making some mistake or lack of sleep. Totally zonked right now, its one of those days when cannot leave a problem alone. Anyway...

sharulgoel

A question on escalator:

Ramesh walked down a descending escalator and took 40 steps to reach the bottom. Suresh started simultaneously from the bottom, taking 2 steps for every step of ramesh.The time taken by Ramesh to reach the bottom from the top is same as taken by suresh to reach the top. How many steps more than Ramesh did Suresh take before they crossed each other on the escalator?

prakharc

Quote:

Originally Posted by sharulgoel

A question on escalator:

Ramesh walked down a descending escalator and took 40 steps to reach the bottom. Suresh started simultaneously from the bottom, taking 2 steps for every step of ramesh.The time taken by Ramesh to reach the bottom from the top is same as taken by suresh to reach the top. How many steps more than Ramesh did Suresh take before they crossed each other on the escalator?

speed of R = 1 step / sec ..time taken by R= 40sec
speed os S = 2 step/sec...time taken by S= 40 sec
speed of escal= e steps/sec
Number of steps in stationary escalator=n
n/(1+e)=40 and n/(2-e)=40 => e=1/2 and n= 60

Now let them cross each other at time t
so (2-e)t + (1+e)t= n => 3t=60 or t= 20 secs...
so sueesh took 20 steps more then ramesh

kapil_kapil · 09:31 AM

two ferry start at same time ,a from goa to mumb and B from mumb to goa ..each boat travels at a constant speed,a A is faster than B ...they pass other point 720 yards from mumb ...both boats stay in their slip for 5 min and then start back ...they pas again 400 yards from goa.assume both boats travel along st line ,then how far is goa frm mumb.

a. 1,120 b. 2,880 c. 2,1 60 d. 4400 e. 2,520