To be considered for this year's Gillespie Grant, applications must be received in Gillespie City by October It can ...

on June 3, 2019


I'm unsure as to why the correct answer in this case is actually the correct answer. In the video lessons I learned that "only if" is equivalent to "if and only if." So, when saying that her application would be reviewed "only if" it was mailed 10 days before excludes all other considerations for it being reviewed. Any help would be appreciated, thanks!

1 Reply

Ravi on June 4, 2019


In the video lessons, "only if" and "if and only if" are not described
as equivalent statements.

"Only if" introduces the necessary condition, whereas "if and only if
is a bi-conditional statement."

I will go to Mars only if I have a rocket

Mars - >rocket

I will go to the movie if and only if David comes with me

Movie< - >David comes

For the question you're asking about, diagramming helps a lot.

Considered for Grant - >Application Received by Oct. 1

Sometimes it takes mail 10 days to get from Greendale to Gillespie

Conclusion: Send application by regular mail - >must mail 10 days
before the due date

The conclusion is incorrect in saying that the mail has to be sent 10
days before the due date. All that we know is that it may take up to
10 days for the mail to get from Greendale to Gillespie, but that
doesn't mean that the mail always takes 10 days. It's possible some
mail arrives well before 10 days.

(C) says, "does not consider the minimum amount of time it takes
regular mail from Greendale to reach Gillespie City"

(C) is precisely what we had anticipated in our analysis. The argument
is not thinking about the possibility that it may sometimes take fewer
than 10 days for mail to go from Greendale to Gillespie. In those
instances, it wouldn't be necessary to mail in an application 10 days
before it's due. Thus, (C) is the correct answer.

Hope this helps. Let us know if you have any more questions!