math question on teasers

[lu_hawk]

I have a friend who made this bet this weekend, he laid down $240 to win $200. It is called a 3 game teaser, in case you haven't heard of it before it is a 3 game parlay but he is able to shift the lines by 6 points in whatever direction he wants. I forget what games he took and what he set the lines at but it is not important for my question.

I don't bet on sports but this seems like a huge sucker bet to me. You need 7-1 to break even on a 3 game parlay with a correct spread, he is able to change the line but now only getting 5-6.

So tell me if this is right. Slansky says in Getting the Best of it that a one point spread is a 2.5% advantage to win the game outright. So if it is normally 50/50 with a correct spread his odds increase to 65% to win each game by shifting the spread 6 points in his favor. So his chance of winning the bet is .65^3=27%. So he would need to be getting close to 3-1 to break even. The thing I am not sure about is if it is appropriate to simply say that he has a 65% chance of winning each game based on Slansky's rule of thumb. Even if my math is wrong I still feel like it isn't even close EV wise and I berated him for taking the bet.

[craig r]

There are certain key numbers that one crosses on a teaser (mainly 3, 7, and 10) that will increase the odds of covering. I think each point is worth 2%, but on key numbers it is worth more. One also has to take into account if he is taking favorites, dogs, home, away. A home favorite, for example, teased from 7.5 to 1.5 covers at around 70% (possibly higher, i can't find the numbers on it right now).

But, a 3 team teaser is usually not a good play. But, the odds are probably not as bad as one would think. I hope some of the above made sense. They were more scattered thoughts on teasers /images/graemlins/laugh.gif.

craig

[kdog]

Laying 6-5 on a 3 team teaser where you only move the lines 6 pts is a HUGE sucker bet. Most sites will lay you 9-5 on this bet. 5Dimes will let you move the lines 9.5 pts and you still only lay 11-10. Your buddy deserved the berating you gave him.