A3

Part of 1958 February Putnam

Problems(1)

Putnam 1958 February A3

Source: Putnam 1958 February

Real numbers are chosen at random from the interval

[0,1].

If after choosing the

n

-th number the sum of the numbers so chosen first exceeds

1

, show that the expected value for

n

e

Putnamprobabilityexpected valueexponential