Patrick from Woodbridge School sent in his
thoughts on some of these statistical statements:
1.There is a small probability of the tail vanishing in mid-air, or
landing on its side, or some such occurrence, so this statement is
false.
2. Let the piece of uranium be one atom. Then it is impossible for
half the mass to decay - either the atom decays or it does
not.
6. If an influenza pandemic occurred last year and killed a
sizeable portion of the population, then a new flu is not likely to
become a pandemic as there are fewer potential carriers who can
spread the disease across the world, so fewer people will come into
contact with the virus and it is not a pandemic.
8. The 40-year old has already passed five years without death, so
the 35-year old has a chance of death before the age of 40. Thus,
the 35-year old has a chance of not making the 40-year old's death
day.
Steve thought:
1. Coin could land on its edge
2. Energy cannot be negative, whereas all normal distributions go
can take negative values
3. Pdfs must have an area of 1 and a semi-circle of radius 1 has
an area of 3.14
4. What happens when there are only a few atoms left? If each atom
decays spontaneously, then the realised loss of mass will not be
exactly one half.
5. The time can only be measured in discrete chunks (depending on
the accuracy of the measuring device), whereas a U(0, 1) rv is
continuous
6. An influenza pandemic is not just as likely to occur one year
as the next events are not independent, viruses mutate and
resistance decreases over time; they are not memoryless. So, the
chance of one increases builds up (very loosely) over time. See
http://community.tes.co.uk/forums/t/314672.aspx
7. The average number of children is a number divided by the total
number of families, whereas the average number of siblings is a
number divided by the total number of children. In a large family
there are lots of children. Each of these has a lot of siblings, so
this has the effect of raising the average number of siblings. To
see this more clearly, imagine that there are 10 families of 1
child and 10 families with 2 children.
The average number of children per family is $(10\times 1+10\times
2)/20 = 1.5$.
The average number of siblings each child has is $(10\times 0 +
20\times 1)/30 = 0.667$
8. As you live longer, you have survived longer. So your expected
age of death actually increases the longer you live. To see this
more clearly, take an extreme case where someone lives beyond the
average age expected at birth!
This short article gives an outline of the origins of Morse code and its inventor and how the frequency of letters is reflected in the code they were given.