Bionic Mamas

you're not losing a vagina, you're gaining a son

Math for Parents: Probability


Yes, this is the same dang thing I just posted on FB, but some of y’all aren’t on there and might want to know I’m not dead.  Plus: posterity.


A bottle of 180 children’s vitamins is divided into three colors (orange, pink, and purple) and four animal shapes (cat, lion, hippo, elephant). Every day, 2 children are presented a selection of approximately 10 vitamins, poured from the top of the jar, from which each selects 2 vitamins, for a total of 4 eaten per day. (The unselected vitamins are returned to the jar.)
IF Child A only wants purple vitamins (without regard to shape) AND Child B only wants cat vitamins (without regard to color), what are the odds each will be pleased with the selection on
– Day 1?
– Day 60?
– Day 90?
For extra credit, at what point in the life of the bottle do the odds of direct conflict between the children over their choices (i.e., the only purple vitamins are cats or vice-versa) rise above 50%? Does it matter which child is allowed to choose first?
Additional discussion: If at least one of the parents of these children believes vitamins are a crock, how did she get into this mess?  (Hint: it involves iron vs. lead absorption.)

3 thoughts on “Math for Parents: Probability

  1. Questions! Do we assume that colors and animal shapes are equally distributed? How is “pleased” defined? Next time let’s do the math on the relative costs and benefits of replacing these vitamins with sad, round, grey ones. Good to know you are alive, lady.

  2. yay, you are not dead!
    and now I’m jealous of such fun vitamins!!!! the only fun bit of kids vitamins is the picture on the bottle. Well, the ones I know of.
    2 x 45 = 90
    4 x 45 = 180
    day 1 is not a problem, day 60 is two weeks and a day after your bottle should be empty. unless child(ren) are not required to actually take unpleasing vitamins.
    What is the probability they change their mind?
    Still so jealous of your problem that the whole iron vs lead doesn’t really grab me. Here only vitamin D for calcium uptake for strong bones is recommended till the age of four. And then again when menopause hits. So for now that is both of us ladies in our household.
    Any news on the schools?

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