SOLUTION: from a bag containing 2 rupee-coins and 3 twenty paise coins, a person is asked to draw two coins at random. find the values of his expectaion

1 rupee = 100 paise

Therefore, a twenty paise coin is  or  rupee-coin.

If he draws:

A.   2 rupee-coins, that = 2 rupee

B.   1 rupee-coin and 1 twenty paise coins that = 1.2 rupee

C.   2 twenty paise coins, that = 0.4 rupee

Number of ways to draw A:  Draw 2 rupee-coins 1 way

Number of ways to draw B:  Draw 1 rupee-coins 2 ways TIMES 3 ways to
draw 1 twenty paise coin.  That is 2x3 = 6 ways. 

Number of ways to draw C:  Draw 2 rupee-coins 3 ways.

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Number of ways to draw ANY 2 coins = 5C2 = 10 ways.

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Probability of A = 
Probability of B = 
Probability of C = 

 Draw  Value x Probability = Expectation 
  A     2    x   0.3            .6
  B     1.2  x   0.6            .72
  C     0.4  x   0.1            .04
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                 1.0           1.36 rupees

Expectation = 1.36 rupees.

Edwin