IIT JEE , AIEEE Forum - Mathematics , Algebra

VIV

Jack's sock drawer contains 10 blue socks and 12 gray socks.  
The room is dark and he cannot turn on the light.  What is 
the least number of socks he must take out of the drawer to 
be certain of each of the following conditions?

a. He has a pair of the same color.
b. He has a pair of the blue socks
c. He has a pair of gray socks.
d. He has one pair of each color.

akhil_o

a)3
b)14
c)12
d)14

VIV

the answers were

3
14
12
14

coolkrazy007

plzzz explain.......

nadeemoidu

Here u have to understand that there is no left socks and right socks . taking any of the socks will go on both foots . using this , it is quite easy to understand.

( actually i dont even care if my socks are of the same type or same colour.

akhil_o

We always have to consider worst-case-scenarios
hance for a) to pick out a pair if we pick up 2 socks the worst case is that they are of diff colors
but in the third lift they will be of either 1 color and hence we have a pair
so a)3

b)for blue socks
in the worst case here we have 12 grey socks in the first 12 lifts
after that grey socks get over and all socks picked will be blue
hence answer is 14
and so on for grey

for 1 pair of each color, the worst case in b) is alrwady considerd hence 14

hope u understand

VIV

gud work friend

coolkrazy007

thnxx a lot

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