Hey everyone,
would anyone be able to elaborate on the clock observation brainteaser? As in, how do you arrive at this particular solution.
Best
K
Hey everyone, here is a longer solution that the preblounge team sent me. Maybe it helps you too.
The hour hand of a clock is exactly on the minute mark five times each hour i.e. on the hour, twelve minutes past the hour, twenty four minutes past the hour, thirty six minutes past the hour and forty eight minutes past the hour. Now we will use an equation with two unknowns to solve the problem. Let us suppose that X are the number of hours and Y are the number of minutes past the hour. When the hour hand is on the minute mark, the position of the hour hand is: 5X + Y/12 The position of the minute hand is: Y Thus, when the first observation is made the corresponding equation is: Y = 5X + Y/12 + 6 This is also equivalent to 60X = 11Y - 72. But from what we know, Y can only be equal to 0, 12, 24, 36 or 48. Thus, the only value possible for X and Y are 1 and 12 respectively. This means that the time is 1:12 when the second observation is made. When the second observation is made the corresponding equation is: Y = 5X + Y/12 + 7 This is also equivalent to 60X = 11Y - 84. The possible values for X and Y here are 3 and 24 respectively. This means that the time is 3:24 when the second observation is made. Now we know the time of the first oberservation and of the second observation and can easily calculate the time that has elapsed between the two of them: From 1:12 till 3:24 it is 2 hours and 12 minutes.
Hi,
It would be helpful if you provide more details.
If that is the case:
"The hour hand is exactly at a minute mark, and the minute hand is six minutes ahead of it in the first glance. When the clock is looked at again, the hour hand is exactly on a different minute mark, and the minute hand is seven minutes ahead of it this time."
Then the solution is:
In the first observation, the time was 1:12. In the second observation, the time was 3:24.
Therefore, 2 hours and 12 minutes have elapsed.
Best
Hey Vlad, thanks a lot for the quick reply. Yes, that's the correct exercise. I saw the solution but was unable to understand how you arrive at it. Would you kindly explain how you got there? Thanks a lot! — on Oct 26, 2017
Hey everyone, here is a longer solution that the preblounge team sent me. Maybe it helps you too. The hour hand of a clock is exactly on the minute mark five times each hour i.e. on the hour, twelve minutes past the hour, twenty four minutes past the hour, thirty six minutes past the hour and forty eight minutes past the hour. Now we will use an equation with two unknowns to solve the problem. Let us suppose that X are the number of hours and Y are the number of minutes past the hour. When the hour hand is on the minute mark, the position of the hour hand is: 5X + Y/12 The position of the minute hand is: Y Thus, when the first observation is made the corresponding equation is: Y = 5X + Y/12 + 6 This is also equivalent to 60X = 11Y - 72. But from what we know, Y can only be equal to 0, 12, 24, 36 or 48. Thus, the only value possible for X and Y are 1 and 12 respectively. This means that the time is 1:12 when the second observation is made. When the second observation is made the corresponding equation is: Y = 5X + Y/12 + 7 This is also equivalent to 60X = 11Y - 84. The possible values for X and Y here are 3 and 24 respectively. This means that the time is 3:24 when the second observation is made. Now we know the time of the first oberservation and of the second observation and can easily calculate the time that has elapsed between the two of them: From 1:12 till 3:24 it is 2 hours and 12 minutes. — on Oct 27, 2017 (edited)
Hello but for me, it is 1 hour and 6 minutes, you can test with any hour, imagine it is around 2 p.m the first observation 2:16 and the second is 3:22 ------? the difference is 1:06
imagine the observation is at 8 p.m ---? 1st observation is 8:46 and 2nd observation 9: 52 ---> the difference is 1 hour and 6 second...... as you can see at all these times, the distance between minute and hour hand are valid...
any elaboration?
Number sequence Situation: “You and I will take turns saying numbers. The first person will say a number between 1 and 10. Then, the other person will say a number that is greater than the first number. The difference between both numbers must be between 1 and 10. We will keep going back and forth ... Open whole case
Motel Situation: Three friends check into a motel for the night. The clerk tells them the bill is $30, payable in advance. They each pay the clerk $10 and go to their room. A few minutes later, the clerk realizes he has made an error and overcharged the trio by $5. He asks the bellhop to return $5 ... Open whole case
Pirates Situation: Five pirates are trying to split up 1000 gold pieces. The rules are as follows: Pirate #1 must divide the gold up in such a way that a majority of the pirates (including himself) agree to. If he does not get a majority vote, he will be killed, and pirate #2 will get to propose ... Open whole case
Firefighter Situation: A firefighter stood on the middle rung of a ladder, spraying water on a burning house. He then climbed up 6 rungs before the heat of the flames caused him to come down 10 rungs. After some minutes he was able to climb 18 rungs to the very top of the ladder. Question: How m ... Open whole case
As a consultant at Mercedes-Benz Management Consulting, you are actively shaping the future of mobility. While you are contributing to decisive projects that design the future of the world’s No.1 premium carmaker, you also develop your own career path and you have the unique possibility to build you ... Open whole case
