If it were two hours later, it would be half as long until midnight as it would be if it were an hour later. What time is it now?
Midnight
#1
Posted 30 March 2007 - 03:51 PM
Midnight - Back to the Logic Puzzles
If it were two hours later, it would be half as long until midnight as it would be if it were an hour later. What time is it now?
If it were two hours later, it would be half as long until midnight as it would be if it were an hour later. What time is it now?
Spoiler for Solution:
rookie1ja (site admin)
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#2
Posted 05 July 2007 - 02:38 PM
9 PM
(1) 9 PM + 2 hrs = 11 PM or (midnight - 11 PM) = 1 hr
(2) 9 PM + 1 hr = 10 PM (midnight - 10 PM) = 2 hrs
So, (1) = 1/2 of (2)
OR straight up:
Where:
X = Solution Time
T = Midnight - X
(a) 12 - (X + 1) = T
(b.1) 12 - (X + 2) = T/2
(b.2) 24 - (2*X + 4) = T
Then:
(a) = (b.2) gives:
(c.1) 12 - (X + 1) = 24 - (2*X + 4)
(c.2) - X - 1 = 12 - 2*X - 4
(c.3) X = 12 - 3 = 9
(1) 9 PM + 2 hrs = 11 PM or (midnight - 11 PM) = 1 hr
(2) 9 PM + 1 hr = 10 PM (midnight - 10 PM) = 2 hrs
So, (1) = 1/2 of (2)
OR straight up:
Where:
X = Solution Time
T = Midnight - X
(a) 12 - (X + 1) = T
(b.1) 12 - (X + 2) = T/2
(b.2) 24 - (2*X + 4) = T
Then:
(a) = (b.2) gives:
(c.1) 12 - (X + 1) = 24 - (2*X + 4)
(c.2) - X - 1 = 12 - 2*X - 4
(c.3) X = 12 - 3 = 9
#5
Posted 07 December 2007 - 06:35 PM
I got the easy answer of course, but wouldn't 10:20 pm work as well if you think of it a bit differently? One hour later is 11:20, 40 minutes away from midnight, 2 hours later would be 12:20, 20 minutes away from midnight. 20 is half of 40(for those who need the help lol)
#6
Posted 11 December 2007 - 02:07 PM
Quote
I got the easy answer of course, but wouldn't 10:20 pm work as well if you think of it a bit differently? One hour later is 11:20, 40 minutes away from midnight, 2 hours later would be 12:20, 20 minutes away from midnight. 20 is half of 40(for those who need the help lol)
Except that the original puzzle states "half as long until midnight". If it were "half as far from midnight", 10:20 pm would work. However, 12:20am is a whopping 23 hours and 40 minutes from the next midnight, which throws the whole thing off...
#8
Posted 01 February 2008 - 08:19 PM
Emapher, on Feb 1 2008, 07:02 PM, said:
why coulnt it be 8pm.
That would be 4 hours until midnight- if its two hours later- its 10pm. which is two hours until midnight.
2 hrs. is half as long as 4 hrs. so why cant this work??
That would be 4 hours until midnight- if its two hours later- its 10pm. which is two hours until midnight.
2 hrs. is half as long as 4 hrs. so why cant this work??
wrong because:
If it were two hours later (10pm), it would be half as long until midnight (2 hours to midnight) as it would be if it were an hour later (at 9pm = remember your starting point is 8 pm = 3 hours to midnight which is not 2x2 hours).
rookie1ja (site admin)
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#9
Posted 13 March 2008 - 11:57 AM
[b]
9pm
let x = the current time.
2 hrs later = x + 2; 1 hrs later = x + 1
the statement means:
12 - (x + 1) = (1/2) {12 - (x+1)}
so 24 - 2x - 2 = 12 - x - 1
x = 24 - 2 - 12 + 1
= 9
[\b]
9pm
let x = the current time.
2 hrs later = x + 2; 1 hrs later = x + 1
the statement means:
12 - (x + 1) = (1/2) {12 - (x+1)}
so 24 - 2x - 2 = 12 - x - 1
x = 24 - 2 - 12 + 1
= 9
[\b]
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