What's this maths method?

Hey all,

Posted this question on the banking forums but no answers as of yet, hoping you guys can help me out:

http://www.youtube.com/watch?v=C63XRBslewo

Scroll to 2:05 - He does something where he 'splits the difference', what's the method here?

Thanks

Reply 1

elldeegee

19

Original post by I'mSet

Hey all,

Posted this question on the banking forums but no answers as of yet, hoping you guys can help me out:

http://www.youtube.com/watch?v=C63XRBslewo

Scroll to 2:05 - He does something where he 'splits the difference', what's the method here?

Thanks

half way between 35 years old and 20 years old.

(35+20)/2 = 55/2 = 27.5 (and you dont say you are 27 and a half years old do you? :P)

or "split the difference" the difference between 20 and 35 is 15. splitting this is basically saying half 15 = 7.5

20+7.5 = 27.5

(edited 12 years ago)

Reply 2

ghostwalker

17

Original post by I'mSet

Hey all,

Posted this question on the banking forums but no answers as of yet, hoping you guys can help me out:

http://www.youtube.com/watch?v=C63XRBslewo

Scroll to 2:05 - He does something where he 'splits the difference', what's the method here?

Thanks

Just take the average of the two.

20 and 35. Average 27.5, and looks like they just went for a whole number around there, so 27.

Reply 3

I'mSet

OP

2

Original post by elldeegee

half way between 35 years old and 20 years old.

(35+20)/2 = 55/2 = 27.5 (and you dont say you are 27 and a half years old do you? :P)

or "split the difference" the difference between 20 and 35 is 15. splitting this is basically saying half 15 = 7.5

20+7.5 = 27.5

Original post by ghostwalker

Just take the average of the two.

20 and 35. Average 27.5, and looks like they just went for a whole number around there, so 27.

Thanks for replying, I understand he has found the half way point between the two ages. The video then goes on to show him writing the following on the page:

20 --- 21-26 --- 27 --- 28-34 --- 35
50 ---- 50 ---- 50 ---- 50 ---- 50
200 --- 150*6 --- 100 --- 75*6 --- 50
200 --- 900 --- 100 --- 450 --- 50

Total 1.7m

I get the second two lines but am interested to how he decides that 50k in year 20 is worth 200k by the time it reaches year 35?

Edit: Ah I think I see now, he just implicitly assumes a 10% annual return.

(edited 12 years ago)

What's this maths method?

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