Here, new technique refers to the design stage is performed in $3,4, \& \hspace{0.1cm} 5^{th} month$ & in the $5^{th}$ month $5$ people are working on the design stage. And the coding stage was finished in $6^{th} - 8^{th}$ months.
The new table will be look like:
| Month |
Stage |
Cost(Rs. '000 per man-month) |
| $1-2$ |
Specification |
$40$ |
| $3-5$ |
Design |
$20$
|
| $6-8$ |
Coding |
$10$
|
| $9-10$ |
Testing |
$15$
|
| $11-15$ |
Maintenance |
$10$ |
The number of people employed in each month is:
| Month |
$1$ |
$2$ |
$3$ |
$4$ |
$5$ |
$6$ |
$7$ |
$8$ |
$9$ |
$10$ |
$11$ |
$12$ |
$13$ |
$14$ |
$15$ |
| No. of people employed |
$2$ |
$3$ |
$4$ |
$3$ |
$5$ |
$5$ |
$5$ |
$4$ |
$4$ |
$1$ |
$3$ |
$3$ |
$1$ |
$1$ |
$1$
|
We can clearly see that, the maintenance stage has the lowest average cost per man-month .
In the $1-5$ month span,
average cost per man-month in $1-2$ month is $40,000$
average cost per man-month in $3-5$ month is $20,000$
So, average cost per man-month in $1-5$ month is = $\dfrac{(40,000+20,000)}{2} = 30,000$
In the $9-13$ month span,
avg. cost per man-month in $9-10$ month is $15,000$
avg. cost per man-month is $10-13$ month is $10,000$
So, avg. cost per man-month in $9-13$ month is $\dfrac{(15,000+10,000)}{2} = 12,500$
In the $11-15$ month span, average cost per man-month is $10,000$
So, the $11-15$ month span will be having lowest average cost per man-month under the new technique.
Answer is option C)