CTS Company HR Interview Interview

There are 1000 doors that are of the open-close type. When a person opens the door he closes it and then opens the other. When the first person goes he opens-closes the doors in the multiples of 1 i.e., he opens and closes all the doors. when the second goes he opens and closes the doors 2, 4 6 8 respectively. Similarly when the third one goes he does this for 3 6 9 12 15th doors respectively. Find number of doors that are open at last.

Read Solution (Total 6)

31 doors are open at last.

perfect square numbers like 1,4,9...961
13 years agoHelpfull: Yes(7) No(18)

Sir please Elaborate your answer
10 years agoHelpfull: Yes(2) No(2)
Pargat .... ur answer is correct.....
10 years agoHelpfull: Yes(2) No(2)
31 doors are open at last.
9 years agoHelpfull: Yes(0) No(1)
please explain
9 years agoHelpfull: Yes(0) No(0)
31. only the perfect squares between 1 to 1k
8 years agoHelpfull: Yes(0) No(0)

CTS Other Question

Two trains are traveling at 18kmph and are 60 km apart. There is fly in the train. it flies at 80 kmph. It flies and hits the second train and then it starts to oscillate between the two trains. At one instance when the two trains collide it dies. Distance traveled by the fly when both trains collide is? There are 9 balls of this one is defective. Find the minimum no. of chances of finding the defective one.