## Sunday, 28 October 2012

### The truth about Robin Hood

I did already mention how much I love my dad, didn’t I?
Only he can turn plain old math riddle into Mad Hatter story. And conclude that Robin Hood is an unreasonably expensive accountant to have.

Four brothers had £45. If the first brother’s money is raised by 2, the second brother’s money is lessened by 2,  the third brother’s money is multiplied by 2, the fourth brother’s money is divided by 2, then everyone has fair do’s. How much money does everyone have?

a+b+c+d=45

And then Robin Hood came and started taking from the rich and giving to the poor, so all of them would have equal amounts (that is £45/4=£11.25)

a+2=11.25           b-2=11.25            2c=11.25            d/2=11.25
a=9.25                   b=13.25                c=5.625                 d=22.5

And check:          a+b+c+d= 9,25+13,25+5,625+22,5=£50.375             which is not exactly £45
Something is not right in Sherwood Forest, because I don't think mr. Hood will add his own money...

Let’s go another way:
a+b+c+d=45
a+2=b-2=2c=d/2
Starting with the first brother:
a+2=b-2               b=a+4
a+2=2c  c=a/2+1
a+2=d/2               d=2a+4
a+(a+4)+(2a+4)+(a/2+1)=45
4.5a+9=45
4.5a=36
a=8

The second brother:
b-2=a+2               a=b-4
b-2=2c                 c=2b-4
b-2=d/2                d=b/2-1
(b-4)+b+(2b-4)+(b/2-1)=45
4,5b-9=45
4,5b=54
b=12

The easiest variant, though, is:
b-2=a+2=10        b=12
2c=a+2-10          c=5
d/2=a+2=10        d=20

Check time:        a+b+c+d=8+12+5+20=45

And when everyone has the same, altogether it will be 40.
Tag line: Robin Hood took £5 as commission fee. 11%, that capitalistic vigilante!