What is the duration of this activity?

1.       An activity has an early start,(ES) of day 13,an early finish (EF) of day 9 and a late finish (LF) of day 19. What is the duration of this activity?

A 3

B 6

C 7

D 10

I'm guessing there is typo in the question how can ES be 13 and EF be only 9?

Its not typo.They want make

Its not typo.

They want make confuse us.  They ask only duration na, simple do LF-LS

i.e 10

there is no LF value in that question. only ES & EF is given.

There is no LF..only LS is given.

based on the question .. the duration is -4 (EF-ES)

but the answer is not available ??

They want make confuse us.    They asl only duration na, simple LF-LS or EF-ES.

i.e 6  ( 10 is the float)

10 is free float value not a activity duration.

<p>LF-EF / LS-ES is free float formula.. Whereas EF-ES is the duration formula.&nbsp;</p><p>&nbsp;</p><p>please correct me if iam wrong.&nbsp;</p><p>&nbsp;</p>

10 is free float value not a activity duration.

LF-EF / LS-ES is free float formula.. Whereas EF-ES is the duration formula.

please correct me if iam wrong.

Some problem in this question for sure

Yes keyveeyen  equations are correct.

LS-ES or LF-EF give the float of the activitity

EF-ES or LF-LS give the duration of the activity

As per the given values float is 10 and duration is -4 (How can -4 be the duration of an activity?)

@JP2786While cut and paste

@JP2786

While cut and paste somebody missed some information somewhere in some website.  Thats why this mistake may conitues for one website onother one.   I searched in the google.  I found this information.  I concludes that the right version of the question may be as follows:

An activity has an early start (ES) of day 3, a late start (LS) of day 13, an early finish (EF) of day 9, and a late finish (LF) of day 19. What is the duration of this activity?

a. 3
b. 6
c. 7
d. 10

Here answer is C. 7 days.

Yup

Looks like thats the correct version. Thanks for posting.

Hi Guys,

As per the above Q : EF-ES or LF-LS = 6. So B should be right one.

ES=3 and EF=9

ES=3 and EF=9

Duration of days = 3,4,5,6,7,8,9 = Seven days
Duration Formula = EF-ES+1

of day 3, a late start (LS) of day 13, an early finish (EF) of day 9, and a late finish (LF) of day 19. What is the duration of this activity?

a. 3
b. 6
c. 7
d. 10
Here answer is C. 7 days.

@typo

@typo

ES=3 and EF=9 Duration of days = 3,4,5,6,7,8,9 = Seven days Duration
Formula = EF-ES+1

Thanks for the clarification

Thanks Sunku65 for the clarification.

why do duration formula is

why do duration formula is sometime calculated as
duration = ES- EF

and sometime as
duration = ES- EF+1

Please explain.when do we prefer which formula.

Its for our convenience:

Its for our convenience:
Some times network diagram starts with ES=0 or ES=1

Example: A=3 days; B=5 days; C=2days
Path = Start-A(FS)-B(FS)-C(FS)-End
Duration = 3+5+2 =10 days

RITA follows below method :

First activity(A) successor of Start :
ES=0
EF =ES Duration=0+3= 3.

Activity B:
ES =Predecessor Activity A's EF becomes successor activity ES. ie. ES=3.
EF=ES Duration = 3+5=8

Activity C:
ES =Predecessor Activity B's EF becomes successor activity ES. ie. ES=8..
EF=ES Duration = 8+2=10

WE follows below method :

First activity(A) successor of Start :
ES=1
EF =ES Duration-1=1+3-1= 3.

Activity B:
ES =Next day of Predecessor Activity A EF becomes successor activity ES; i.e. ES = 4
EF=ES Duration-1 = 4+5-1=8

Activity C:
ES =Next day of Predecessor Activity B EF becomes successor activity ES;
i.e ES=9.
EF=ES Duration-1 = 9+2-1=10

Depending on given network diagram.
If network diagram starts with 0 as ES, then apply 1st one.
else network diagram starts with 1 as ES, then apply 2nd one

If anything wrong correct me.
Thanks,
Lax