compute expected value of Taiwan invoice

invoice_expected_value.rb

=begin
#--- OUTPUT :
0.1
0.02
0.005999999999999999
0.012
0.030000000000000002
0.12000000000000001
0.3
1.0
"Expected Value : 1.588"
=end

# Value of money
# m = million, t = thousand, h = hundred
v10m     = 10000000
v2m      = 2000000
v200t    = 200000
v40t     = 40000
v10t     = 10000
v4t      = 4000
v1t      = 1000
v2h      = 200
# Probability 
p10m     = 1.0/100000000
p2m      = 1.0/100000000
p200t    = 3.0/100000000
p40t     = 3.0/10000000
p10t     = 3.0/1000000
p4t      = 3.0/100000
p1t      = 3.0/10000
p2h      = 5.0/1000

# EV : expected values 
p e10m  = v10m   *  p10m
p e2m   = v2m    *  p2m
p e200t = v200t  *  p200t
p e40t  = v40t   *  p40t
p e10t  = v10t   *  p10t
p e4t   = v4t    *  p4t
p e1t   = v1t    *  p1t
p e2h   = v2h    *  p2h

# Sum of EV
sumEV = e10m+e2m+e200t+e40t+e10t+e4t+e1t+e2h
p "Expected Value : #{sumEV}"