CAT 2000 — QA Question 25
Answer the following question based on the information given below.
There are five machines A, B C, D and E situated on a straight line at distances of 10 metres, 20 metres, 30 metres, 40 metres and 50 metres respectively from the origin of the line. A robot is stationed at the origin of the line. The robot serves the machines with raw material whenever a machine becomes idle. All the raw material is located at the origin. The robot is in an idle state at the origin at the beginning of a day. As soon as one or more machines become idle, they send messages to the robot-station and the robot starts and serves all the machines from which it received messages. If a message is received at the station while the robot is away from it, the robot takes notice of the message only when it returns to the station. While moving, it serves the machines in the sequence in which they are encountered, and then returns to the origin. If any messages are pending at the station when it returns, it repeats the process again. Otherwise, it remains idle at the origin till the next message(s) is received.
Suppose on a certain day, machines A and D have sent the first two messages to the origin at the beginning of the first second, and C has sent a message at the beginning of the 5th second and B at the beginning of the 6th second, and E at the beginning of the 10th second. How much distance in metres has the robot travelled since the beginning of the day, when it notices the message of E? Assume that the speed of movement of the robot is 10 metres per second.
Answer & solution
140
- B
80
- C
340
- D
360
Machines A and D sent message at the beginning of the first second.
∴ Round 1: Origin to Machine A to Machine D to Origin
Distance covered by the robot = 80 m (40 m + 40 m)
Time taken to return to origin = 8 seconds
At the end of 8th second, messages from C and B are already received,
∴ Round 2: Origin to Machine B to Machine C to Origin
Distance covered by the robot = 60 m (30 m + 30 m)
Time taken to return to origin = 6 seconds
Total Time elapsed = 8 + 6 = 14 seconds
At the end of 14th second, message from E is already there.
The robot has travelled 140 m (80 m + 60 m), when it notices message from E.
Hence, option (a).