Question 1024835: Problem 9
Ali will take the
:11:41 AM
train to San Diego. The train is estimated to arrive in San Diego in
3
hours
39
minutes. What is the estimated arrival time?
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! the train leaves at 11:41 am.
the train take 3 hours and 39 minutes.
the time of departure is 11 hours and 41 minutes in 24 hour time.
you want to add 3 hours and 39 minutes to 11 hours and 41 minutes.
do the minutes and the hours separately.
you get a total of 14 hours and 80 minutes.
since 80 minutes is equivalent to 1 hour and 20 minutes, then you want to take away 60 from the minutes part of the answer and add 1 to the hours part of the answer.
you get a total of 15 hours and 20 minutes.
that's in 24 hour time.
to convert from 24 hour time to 12 hour time, you need to subtract 12 hours from the 24 hour time if the 24 hour time is greater than 12 - otherwise you just leave it as is.
therefore 15 hours and 20 minutes in 24 hour time is equal to 3 hours and 20 minutes in 12 hour pm time.
the pm hours become 15 - 12 = 3.
the pm time becomes 3 hours and 20 minutes.
this is shown as 3:20 pm.
the train leaves at 11:41 am.
the train arrives at 3:20 pm.
to calculate the time it took, convert the 12 hour time to 24 hour time.
the 12 hour am time is still 11:41 - no adjustment necessary there.
the 12 hour pm time is 3:20 plus 12 = 15:20 in 24 hour time.
now you want to subtract 11:41 from 15:20.
you are subtracting 3 hours and 41 minutes from 15 hours and 20 minutes.
take 1 away form the hours time and add 60 to the minutes time of 15:20 to get 14 hours and 80 minutes.
now you can subtract 11 hours and 41 minutes from 14 hours and 80 minutes.
11:41 is the departure time in 24 hour time.
14:80 is the arrival time in 24 hour time, after the adjustment.
subtract 41 minutes from 80 minutes to get 39 minutes.
subtract 11 hours from 14 hours to get 3 hours.
the time it took is 3 hours and 39 minutes.
this corresponds to the number of hours and minutes it took from the problem statement so the solution can be determined to be correct.
your solution is that the train arrives at 3:20 pm.
note:
12 hour time is broken up into two segments of 12 hours each.
the first segment is am time.
the second secoment is pm time.
24 hour time take the whole day as 24 hours rather than two segments of 12 hours apiece.
most clocks show 12 hour time.
you have to know whether it's am or pm in order to correctly read the clock.
to convert from 12 hour time to 24 hour time, you add 12 to the pm time.
to convert from 24 hour time to 12 hour time, you subtract 12 from the 24 hour time, only if the 24 hour time is greater than 12.
some examples.
9:00 am is equal to 9:00 in 24 hour time.
9:00 pm is equal to 9 + 12 = 21:00 in 24 hour time.
23:45 in 24 hour time is equal to 23 - 12 = 11:45 in 12 hour time.
when adding and subtracting minutes, you do the hours and minutes separately.
if the number of minutes you are subtracting is greater than the number of minutes you are subtracting form, then you need to borrow 1 from the hours and add 60 to the minutes.
this is the same as i did above.
|
|
|
