Question

A had in his pocket a 100 rupee note and 4 100 rupee notes ,taking out 2 notes at random he promises to give them to B and C. What is the worth of C's expectation?

(Answer is Rs. 28)

Answer 1

There are 1 Rs.100 note and 4 Rs.10 notes
(I think you have typed 100 instead of 10 there)

So, he takes 2 notes and gives 1 to each of B and C,

So, B and C has same expectation

Expectation will be=

Probability of Rs.100 [ 100 ] + Probability of Rs.10 [ 10 ]

Prob of Rs.100 note = 1/5

Prob of Rs.10 note = 4/5

So,

Exp = 1/5 (100) + 4/5 (10)

= 20 + 8

= 28

Therefore expectation of C is Rs.28