[I have redirected this from general forum to chat forum, since that
seems appropriate. Maybe I've got enough code here for the programming
forum, but I couldn't resist the urge to also chat about it a bit.]

Or */34#0.99 (this approach becomes handy when some of the
probabilities are different and also is a step on the way towards
dealing with other kinds of combination of probability issues).

That said, note:

(1) for covid-19, the recent estimates on mortality rate were 0.7%.

(2) If life expectancy of a population is 100 years and the size of
the population is stable, that means 1% of the population dies every
year (this is somewhat significant in today's context, since the age
curve for covid-19 deaths approximately matches the age curve for
deaths from all causes. To get a better sense of the actual impact of
the disease we'll want to be checking the mortality totals for this
year against the totals for previous years. But we probably won't have
those for the usa for a couple years, given the current state of
affairs. We know it's serious because of hospital crowding issues, and
because some people have long term lingering after effects, but that
0.7% fatality number is only a part of the picture even when we are
only focusing on the chance of death.)

So, ... anyways, for even more fun:

   +//.@(*/)/ 34#,:(,-.)-.0.007
0.787543 0.188757 0.0219551 0.00165087 9.01909e_5 3.81472e_6
1.29975e_7 3.66494e_9 8.71946e_11 1.7757e_12 3.12938e_14 4.81311e_16
6.50311e_18 7.75799e_20 8.20331e_22 7.7104e_24 6.45445e_26 4.81761e_28
3.20743e_30 1.90402e_32 1.00666e_34 4.73085e_37 1.97065...

78.8% chance of no one dying (rounding to one digit after the
percentage decimal place)
18.9% chance of one person dying
2.2% chance of two people dying
0.2% chance of three people dying
etc.

Take care,

-- 
Raul

On Thu, Oct 8, 2020 at 12:45 AM Devon McCormick <[email protected]> wrote:
>
> If 34 people have a disease which is fatal about 1% of the time, what is
> the chance that no one in the group dies?
> )
> 2020 10 7 23 42 40.156
>    0.99^34
> 0.710553
>    34^~-. 0.01  NB. Stating it another way
> 0.710553
>
> --
>
> Devon McCormick, CFA
>
> Quantitative Consultant
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
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