Math Question

I am about as mathematically challenged as an otherwise reasonably bright person can get, so please don't mock me for asking what is probably an easy question. But I cannot figure out the formula on my own, so I throw myself at the mercy of you terrific DG friends.

So here it is:
If I have two Lindera benzoin plants, the odds are 50% that I have both a male and female. I hope that's right. Anyway, what are the odds of having both sexes if I have three plants? Four? Five? Etc. Thanks.

Scott

If you have two plants, you have three possible results:
•two males
•two females
•one male and one female

If you have three plants, you have the following possible results:
•three males
•three females
•two males and one female
•two females and one male

Etc. Figure out your percentages like that. Draw up a grid. Ask will_mckenna, since he probably still remembers the formula from algebra/trig/calc that has long ago turned moldy in my mind.

Are they from different seeds or clones?

Call my husband at home tonight and ask him. Math was my downfall but he always seems to know these formulas and is able to pull them out of the air.

With 2 plants, you have 50% chance of getting one of each (this is because each plant has a 50/50 chance of being either sex, so you have 4 possible plant combinations and 2 of the possible combinations give you the mixed sex you're looking for)
Combo #1: Plant 1 is male, plant 2 is male
Combo #2: Plant 1 is female, plant 2 is female
Combo #3: Plant 1 is male, plant 2 is female
Combo #4: Plant 1 is female, plant 2 is male
Combo 3 or 4 both give you what you want.

With 3 plants, I think you get 8 total combinations (1 combo of all male, 1 of all female, 3 different possible combos where 1 plant is male and the other two are female, and 3 possible combos where 1 plant is female and the other two are male). 6 out of 8 of these combos (or 75%) give you one of each. And your odds will just keep going up as you get more plants but you'll never quite get to 100% certainty. This is all assuming of course that there truly is a 50/50 chance for each one to be either male or female...if there's some other factor at work which makes it more likely for their to be one sex or the other then it complicates things

It's not difficult. If N is the number of plants, the total number of combinations is 2 to the Nth power. Since there are only two possibilities of all one sex (all male and all female), the number of 'mixes' (some male and some female) is 2 to the Nth power minus 2. The number of mixes divided by the total gives the fraction that are mixes. Just multiply this by 100 to give the % odds that there are males and females.

For example, if there are 6 plants, there are 2 to the 6th power, or 64. Percentage of mixes is (62/64) * 100 = 97% (rounded). 3 gives 75%. 4 gives 87.5%. 5 gives 93.75%, etc.

Hope I did not confuse anyone. Having grown up in NYC, it's the certainty of one or the other which I find difficult to grasp.

Victor

That is just great Vib Val. Now I am the resident engineer on these forums. I have enough engineering crap to deal with 9-5 and now I have to answer your guys math & science questions. For the record, probability wasn't my strong suit, unless you figure the probability I was at a bar when I should have been doing homework.

The formula for that isn't too simple since they are independent and exclusive variables. Sounds like a job for binomial distribution...There is no way I can type the formula here since I can't even do scientific text in Microsoft, yet alone in this little box. Here is a link to a site that has a binomial formula for this problem and you just fill in the variables and do the math. I say do like VibVal and ecrane said for simplicity. Or better yet, just get three plants and you have a 75% chance of success and give the one extra one to me since I have not yet had the pleasure to grow a lindera.

Bi = Are there TWO possible outcomes? (i.e., yes or no, win or lose)
Nom = Is there a fixed NUMBER of observations or items of interest?
I = Is each observation INDEPENDENT?
Al = Is the probability for ALL outcomes equal?

http://cnx.org/content/m10244/latest/

edited for stupid spelling errors and for being a nerd

This message was edited Jun 12, 2006 9:34 PM

This message was edited Jun 12, 2006 9:40 PM

Wait until they flower and look at their private parts.

Guy S.

Oops, another correct and easier response came in while I searched the web for an answer. Sorry Viburnum Valley, statistics were the first thing to go when I started learning latin names. Five years of college down the drain.

Way to go, Willis! That's a great interpretation of the terminology.

I went through metallurgical engineering (maybe a few years before you started imbibing) so I understand the nerdidity and the annoyance at being asked to come up with the right change for small purchases (much less the correct proportions for Ni-Cr steel).

One should never let on, but you let the cat out of the bag some time ago. Gray matter is much better served as storage for binomial nomenclature.

What ecrane and victor said: there's some geekosity slipping out there too.

For those that care beyond the arithmetic/statistics/formulae, there's a young woman researcher at the University of KY who is studying the propagation of Lindera benzoin, and natives of Louisville's park system are her guinea pigs. She is starting her second season of collecting plant parts (cuttings this week; seeds last fall). I hope to be able to report successful results here in the future.

VibVal, there is no way I made that little pneumonic trick up. I stole that from some web site, hook line and sinker. I figured it was so nerdy that I couldn't help myself. No geekosity here, at least not compared to Guy and Kevin with their trash talk'n in the Who am I? thread.

You must of had some real winners with the metallurgy. I started in Ceramic Engineering and that was pretty bad. I made the switch to Environmental Engineering once I saw what my future class load and mates would be like.

Bill

And I made a bracelet last night. All by myself. Well o.k. a little bit of help, it was my first time after all. How many of yous guys can say that??? HUH???

terryr:

Well, back in my metallurgy days I could say it, a lot. Casting and welding class was a blast (sometimes, literally, if there was excess moisture in the molds). Bracelets, amulets, etc...you could have been Wild Raisin, Warrior Princess if you took an inkling.

Bill:

I resemble that remark!

Well, we didn't have too many, considering we were the smallest department at Anderson Hall (and banished to the seventh floor). We did have a good view of the sunny beach from there, though. There were a grand total of five of us in my class, maybe twenty total students in the entire department (including grad students). There were five professors. Great ratio, but too much inbreeding. If one wanted to live out one's life in the dinosaur industries of the day (Al and Steel), there you go. If one was interested in making a difference, well, you needed to go to a different school besides that.

The key is to use the geekosity/nerdidity to advantage, much as EQ and Wild Raisin use the blondiferousness.......

Blondiferousness, how would you say it... "I resemble that remark"! In just another year when I turn 50, I'm going to switch over to "gray matter moments" instead of "blond moments". I think the timing will be good. A few after that, terryr can join me in gray matter moments.

I made a few silver inlay bracelets, a cast ring, and an assortment of other jewelry items in High School. Does that count for anything? I went to a bead party and made my niece a fairy princess set which included earrings, a bracelet, a necklace, and a tiara. I'm happening!

Yes, but John....I know my bracelet is far better than any bracelet you ever made. It's sparkly and everything!

Sorry Equil, we were typing over each other......It will be many many many years before I turn gray! I will certainly come to your aid though when you're having a gray matter moment. And of course it counts that you made jewelry! You would know how to make it properly after all! Not the he-men pound thy chest ones. That's where I went, a bead party of some sort. Fun...lots of girl talk and trashing the husbands.....and you wouldn't believe who's sleeping with who now!!! Oh my!

Oops, sorry about that. I thought you were only a couple years younger than me. Well, I'll be anxiously waiting for you to join me in "gray matter moments".

Eeek, one of those parties. Those are very scary to me. I like the husband bashing element although mine does very little wrong. Now children bashing is right up my alley. Mine slip up all the time and I love comparing notes about other people's little darlings. Makes us all feel as if our kids are normal.

Years, I'm telling ya, I've got years before those gray moments happen!!

Mine does very little wrong also. But it sure was fun to listen to the others! I got to hear all kinds of dirty details........And it was really funny when the husband of the hostess came in and visited.....boy did he have details the women didn't know!