An awsome puzzLe
Four
friends
A
,
B
,
C
,
D
need to cross a bridge.
A
maximum
of
2
peoples can cross at a time.
It is night and they have just
1
lamp
.
People that cross the bridge
must
carry
the
lamp
to see the way.
A pair must walk together at the
speed
of
slower
person
.
Speeds of
A
:
1
minute
to cross bridge.
B
:
2
minutes
to cross bridge.
C
:
7
minutes
to cross bridge.
D
:
10
minutes to cross bridge.
What is the
total
minimum
time
(in minutes) required by all 4 friends to cross the bridge ?
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First A and B will cross (2min).
Then A will return with lamp (1min).
Then C with D will cross (10min).
Then B will return with lamp (2min).
Then A with B again (2min).
Hence Total Time = 2+1+10+2+2 = 1 7 M i n u t e s