**Hourglass Problem**

Having 2 sandglasses: one 7-minute and the second one 4-minute, how can you correctly time 9 minutes?

**For Solution**: Click Here

This Blog is a collection of brain teasers, puzzles (maths,fun,brain etc), riddles,Questions, Quiz.

Having 2 sandglasses: one 7-minute and the second one 4-minute, how can you correctly time 9 minutes?

Subscribe to:
Post Comments (Atom)

Difficulty Level 3/5
(727)
Logic Puzzles
(483)
Difficulty Level 4/5
(458)
Riddles
(364)
Difficulty Level 2/5
(358)
Maths Puzzles
(344)
Picture Puzzles
(331)
Trick Teasers
(282)
Popular Puzzles
(212)
Rebus Puzzles
(155)
Humor Puzzles
(151)
Interview Puzzle
(124)
Series Puzzles
(124)
What Word Am I
(99)
Difficulty Level 1/5
(90)
Trivia
(76)
Mystery Puzzles
(73)
Equation Puzzles
(72)
Difficulty level 5/5
(53)
Murder Mystery Puzzles
(43)
Square Count
(40)
Who Am I
(40)
Probability Puzzles
(39)
IAS-EXAMS
(34)
Cipher Puzzles
(32)
Algebra
(31)
Science Puzzles
(30)
Situation Puzzles
(28)
Puzzles of Age
(21)
Read Between Lines Puzzles
(18)
Google Interview Puzzle
(17)
MatchSticks-Riddles
(15)
Microsoft Interview Puzzles
(15)
statement
(15)
Time Distance Problem
(14)
Odd One Out
(13)
Relationship Puzzles
(11)
Cards
(10)
Story Puzzles
(10)
Paradox Puzzles
(9)
Classic
(6)
Directional Puzzles
(6)
Best Of 2011
(5)
clever
(5)
Brain-Twister
(4)
Mind Games
(4)
Analytical
(3)
What Does This Text Mean
(3)
CHALLENGING
(2)
Double Meaning
(2)
chess
(2)
Acronym
(1)
Measure
(1)
Suduko
(1)
Video Riddle
(1)
coin-Puzzles
(1)
m
(1)
pop
(1)
triv
(1)

If you can wait 16 minutes then

ReplyDeletestart 7 & 4 , reversing 4 when it is over.

When 7 gets over, 4 will have one minute sand left.

Use that plus twice 4 to get 9 minutes.

Will be interesting to see it done in less time:-)

first start both 7 and 4 hour glasses(hg) after 4 mins 4hg will be emptyand time is 4m

ReplyDeleteagain reverse 4 hg after 3m 7hg is empty time is 4+3=7m

in reversed 4hg 1m sand is left also reverse 7 hg after 1m 4hg will get empty time is 7+1=8m and rev 7 hg as it has 1m sand revd for 9thmin 7

hence calculated 9 mins

take 7 & 4 do both now when we hav claculated 4 mins we hav 3 mins remaning in 7 one now reverse both after 3 mins we hav 1 min remaining in 4th one now reverse 1 mins so we hav 5mins now add 4mins to it !!!!!!!!!!!!!!!!!!!!!!!

ReplyDeletereverse both the sand glasses at a time, so that we get 3 mins.if we do this for 3 times we get 3+3+3=9

ReplyDelete