Hi
You still haven't given all the facts.
We don't know how many men there are in each crew.
We don't know how many hours it takes to construct a store.
Maybe these are two variables your tutor wants you to consider.
I'm not sure about the 35 months, 34 months periods you mention, as compared
with the time period 01 Mar 08 through till 31 Aug 2011 (which is 42
months).
Perhaps the following will give you a start.
In A1 enter 01 Mar2008
Grab the fill handle at the bottom right corner of cell A1, hold down your
right mouse button and drag down to cell A43.
As you release the mouse button select fill Months. You should have dates
going from 01 Mar 08 to 01 Sep 2011.
In B1 enter
=IF(MONTH(A1)<4,24,48)
which will give the number of Hours worked by 1 man for that month.
Again fill down.
In cell D1 enter
=SUM(B1:B43)
This gives the total hours for 1 man for the whole 42 months
In E1 enter a value as a guess as to the number of hours it takes to
construct a store - say 10,000
In E2:J2 enter the numbers 1 through 6 - the number of stores
In D3
32 enter the number 1 through 30 - the number of men
In E3 enter the formula
=($E$1*E$2)/($D$1*$D3)
Copy across through F3:J3
Copy E3:J3 down through E4:E30
Looking at column I, (5 stores), you are looking for a value of 1 or under.
This occurs at I30, which reading back to column D, shows that it could be
achieved with 28 men.
As you alter the value in cell E1 - the total hours to build a store, then
you will see how many men you need to complete it within the 42 months from
Mar 08 till Aug 11.
At least this should give you something to start with.