142 Financial Management
independent of the cash flow for year i-r. Put differently, there is no relationship
between cash flows from one period to another. In this case the expected net present
value and the standard deviation of net present value are defined as follows:
NPV A
i
i
t
t
n
=
+
- =
( 1 )^1
1
...(8.2)
=
+
s = s
...(8.3)
where NPV = expected net present value
At = expected cash flow for year t
i = risk-free interest rate
t = initial outlay
s(NPV) = standard deviation of net present value
s 1 = standard deviation of the cash flow for year t.
Note that in the above formulae the discount rate is the risk-free interest rate because
we try to separate the time value of money and the risk factor. This risk of the project,
reflected in s (NPV) is considered in conjunction with NPV computed with the risk-
free discount rate. If
NPV
is computed using a risk-adjusted discount rate and then
if this is viewed along with s (NPV), the risk factor would be doubled counted.
Example: A project involving in outlay of Rs. 10,000 has the following benefits associated
with it.
Year 1 Year 2 Year 3
Net cash flow Probability Net Cash flow Probability Net Cash flow Probabilty
Rs. Rs. Rs. Rs. Rs. Rs.
3,000 0.3 2,000 0.2 3,000 0.3
5,000 0.4 4,000 0.6 5,000 0.4
7,000 0.36 6,000 0.2 7,000 0.3
Calculate
NPV
and s (NPV), assuming that i = 6 per cent
NPV A
i
i
t
t
n
=
+
- =
( 1 )^1
1
I
=
5 000
1 06
4 000
1 06
5 000
1 06
, 2 3 10 000 2 475
(. )
,
(. )
,
(. )
+ + = , = ,
=
=
+
s = s