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Produce => Edible Plants => Topic started by: Chrispy on September 19, 2011, 09:27:42

Title: A bit of maths
Post by: Chrispy on September 19, 2011, 09:27:42
If you grow 5 plants from a packet of T&M Winter Squash 'High Sugar Mixed' (http://www.thompson-morgan.com/vegetables/vegetable-seeds/pumpkin-squash-and-courgette-seeds/squash-high-sugar-mixed-f1-hybrid-winter/883TM) that is advertised as a mix of 4 different varieties, what is the probability that all 5 plants will be the same variety?
Title: Re: A bit of maths
Post by: pumkinlover on September 19, 2011, 09:30:05
Well my maths o level was a long time ago so I'll take a miss on this one ;)
Title: Re: A bit of maths
Post by: OllieC on September 19, 2011, 09:33:38
Assuming that it's truly random and taken from a huge pile, isn't it (1/4)^5=1/1024 - roughly 1 in a thousand?
Title: Re: A bit of maths
Post by: saddad on September 19, 2011, 09:52:17
What Ollie said!
Although seed mixes are notoriously difficult to keep mixed as they settle out by size...  :-X
Title: Re: A bit of maths
Post by: Unwashed on September 19, 2011, 10:45:35
Quote from: OllieC on September 19, 2011, 09:33:38
Assuming that it's truly random and taken from a huge pile, isn't it (1/4)^5=1/1024 - roughly 1 in a thousand?
It's 4 x (1/4)^5 - roughly one in 250.  It's 1 in a thousand for any variety, but there are four varieties.
Title: Re: A bit of maths
Post by: Chrispy on September 19, 2011, 12:53:17
If it was random it would be 1/256, as unwashed said, there are 4 varieties.

But who said it was random, this is the evil empire we are talking about, they have problems getting the amount of seeds in the packet anywhere near what it says on the packet.

Having said that, I have just harvested and cleared away the Bonbons, and the remainder of the plants are easier to see.

I thought I had 5 'Celebration', but it turned out 2 of them were the same plant, and I found a 'Table Star' hiding in a hole, so it is not as bad as I first thought.

I'll have to see what the remainder of the seeds produce next year.
Title: Re: A bit of maths
Post by: OllieC on September 19, 2011, 13:00:54
I don't quite understand why you multiply by 4.

Title: Re: A bit of maths
Post by: Chrispy on September 19, 2011, 13:12:28
Quote from: OllieC on September 19, 2011, 13:00:54
I don't quite understand why you multiply by 4.
I would not multiply by 4, rather think of it is like this....

The first plant can be any variety, so the odds are 1/1

The next 4 need to be the same variety with the odds 1/4, so you have

1/1 x 1/4 x 1/4 x 1/4 x 1/4
= 1/1 x (1/4)^4
=(1/4)^4
=1/256
Title: Re: A bit of maths
Post by: Bugloss2009 on September 19, 2011, 13:35:21
if you specify which type you want, say type A, it's 1/1000. If you don't care which type, so long as they are all the same, it's 4x(1/100) ie 1/250
Title: Re: A bit of maths
Post by: Unwashed on September 19, 2011, 13:45:06
Quote from: OllieC on September 19, 2011, 13:00:54
I don't quite understand why you multiply by 4.
Because there are 4 ways to get all the varieties the same: all variety #1, all #2, all #3, and all #4.  The probability of all five plants being any given variety is 1 in 1024 as you say, so the probability of all five plants being the same variety is the sum of the probabilities for all #1 (1 in 1024) + all #2 (1 in 1024) + all #3 (1 in 1024) + all #4 (1 in 1024) == 4 x 1 in 1024 == 1 in 256.
Title: Re: A bit of maths
Post by: VegBob on September 19, 2011, 14:00:30
You mathematicians appear to have overlooked a crucial factor. T&M claim that each packet contains 10 seeds. If they don't contravene the appropriate Sale of Goods legislation only a maximum of 7 seeds can be the same variety. I wait to see your new calculations with interest.
Title: Re: A bit of maths
Post by: pumkinlover on September 19, 2011, 14:09:27
May I suggest that instead anyone who wants a mixture looks at the Seeds of Italy mixed box of squashes and pumpkins.
I bought a box about 5 years ago and have kept dibbing into it till used it up this year.
I had good germination rates, loads of different varieties and no maths to worry about :D :D :D

(I'm assuming what the suggestion is in the original post that instead of picking one seed from each of five varieties T and M just put in 5 seeds of one variety) :-\
Title: Re: A bit of maths
Post by: Bugloss2009 on September 19, 2011, 14:39:24
mixed seeds can be a bit of a disaster. You always seem to end up with lots of one sort, and if it's interesting stuff like mixed species of perennials or whatever, it can be years before you work out what you've got, if ever (step forward 1980's T&M eucalyptus, rhododendron and primulas for instance)

and with mixed salads, all the round seeds come out of the packet first  :) Lots of brassica types then
Title: Re: A bit of maths
Post by: macmac on September 19, 2011, 15:05:26
I sowed about 20 seeds from a T &M pack of mixed chillies red,orange and yellow.
Guess what every plant had yellow chillies.
I'll sow the rest of the packet next year,I'm not holding my breath.....