432 VALUATION, DEPRECIATION AND THE RATE-BASE 
EXPLANATION OF TABLE 31 
EXPECTANCY AND REMAINING VALUE 
Ari ARTICLES AssuMeED 70 Fam WitEIN A TERM EQUAL TO TWICE 
THEIR ORIGINAL EXPECTANCY 
(Approximate Values Only) 
The expectancy of any article in use, which is still in service- 
able condition, can be approximated from the following tables, 
when the probable life new of other articles of the same class is 
known. There is noted in these tables also the approximate 
remaining value, although this may also be obtained from the 
Amortization or Depreciation Table 33 by entering the same 
with the years of expectancy as elsewhere explained. The ex- 
pectancy noted in Table 31 is based on a reasonable assumption 
of the rate at which a large number of articles of the same prob- 
able life would go out of use (see Chapter VI)* and is in fair 
accord with the expectancy that would be found if all the articles 
were assumed to fail according to the law of probabilities within 
a period equal to twice the probable life term. The strict appli- 
cation of the law of probability under assumptions, relating 
not only to the probable life of any article in question, but also 
to the probability of survivals beyond some period, as, for ex- 
ample, twice the probable life, would be an unnecessary refine- 
ment not justified until a vastly greater mass of data than now 
available, relating to actual life of individual articles in each 
class, has been assembled. 
It may be claimed for this table in its present form that it 
will afford means of making much closer approximation to the 
actual remaining worth of any article than is possible by the 
use of the ordinary amortization tables in which age alone is 
taken into account and in which no distinction is made between 
actual and probable life. 
In this table the expectancy and remaining value are noted 
for any single article, whose probable life when new is known. 
The table has been computed for 4 per cent, 5 per cent, 6 per 
cent and 7 per cent interest per annum. For other interest 
rates, values may be interpolated. 
* Page 104 of “Valuation, Depreciation and the Rate-Base.”