Répertoire des administrateurs & commissaires de société, des banques, banquiers et agents de change de France et de Belgique

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Monograph

Identifikator:: 1751319059

URN:: urn:nbn:de:zbw-retromon-129553

Document type:: Monograph

Title:: Répertoire des administrateurs & commissaires de société, des banques, banquiers et agents de change de France et de Belgique

Place of publication:: Paris [u.a.]

Year of publication:: [1926]

Scope:: 1316 S.

Digitisation:: 2021

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Répertoire des administrateurs, commissaires, liquidateurs, curateurs, etc., de sociétés

Collection:: Economics Books

312 THEORY OF STATISTICS. The standard-deviation is /0'5 x 0-5 x 100 = 5. Taking the distribution as normal, y,= 797-9. The mean number of heads being 50, 65 —50=30c. The frequency of a deviation of 3¢ is given at once by the table (p. 303) as 7979 x 0111 . . . . =8'86, or nearly 9 throws in 10,000. A throw of 65 heads will therefore be expected about 9 times. The frequency of throws of 65 heads or more is given by the area table (p. 310), but a little caution must now be used, owing to the discontinuity of the distribution. A throw of 65 heads is equivalent to a range of 64'5-65'5 on the continuous scale of the normal curve, the division between 64 and 65 coming at 64°5. 64:5 — 50 = + 2:90, and a deviation of + 2:9. or more, will only occur, as given by the table, 187 times in 100,000 throws, or, say, 19 times in 10,000. Fxample ii.—Taking the data of the stature-distribution of fig. 49 (mean 67°46, standard-deviation 2-57 in.), what proportion of all the individuals will be within a range of + 1 inch of the mean { 1 inch =0-3890. Simple interpolation in the table of p. 310 gives 0'65129 of the area below this deviation, or a more extended table the more accurate value 0:65136. Within a range of + 0°389¢ the fraction of the whole area is therefore 0:30272, or the statures of about 303 per thousand of the given population will lie within a range of +1 inch from the mean. Example iii.—In a case of crossing a Mendelian recessive by a heterozygote the expectation of recessive offspring is 50 per cent. (1) How often would 30 recessives or more be expected amongst 50 offspring owing simply to fluctuations of sampling? (2) How many offspring would have to be obtained in order to reduce the probable error to 1 per cent. ? The standard error of the percentage of recessives for 50 observations is 50 A/ 1/50 =7'07. Thirty recessives in fifty is a deviation of 5 from the mean, or, if we take thirty as representing 29'5 or more, 4'5 from the mean; that is, 0'636.0. A positive deviation of this amount or more occurs about 262 times in 1000, so that 30 recessives or more would be expected in more than a quarter of the batches of 50 offspring. We have assumed normality for rather a small value of n, but the result is sufficiently accurate for practical purposes. As regards the second part of the question we are to have "6745 x 50 /1/n=1, n being the number of offspring. This gives n=1137 to the nearest unit.

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