Of the 75 houses in a certain community, 48 have a patio

[RonPurewal]

Any Chance that some expert might reply to my question.

When to use a Venn Diag & when to use a 2 set matrix for [2 overlapping sets] .

The examples are listed above.

don't do this -- i.e., don't post a message that says "please answer my question".
this is called "bumping" the thread; it brings the thread up to the most recent position in the folder.

the problem, of course -- on top of the obvious rudeness of this practice (not even 24 hours after your post!) -- is that we answer the posts strictly in order from oldest to newest. therefore, if you post a message, with no content, that says "please answer this post", then you are moving the thread to the LAST place in the queue.

please be patient -- we will get to all of the threads. if you make posts like this one, you're just making it take longer.
thanks.

[RonPurewal]

it's hard to format these questions here, so i'll just give descriptions of what you'd see.

1) A seminar consisted of morning session and afternoon session. If each of the 128 people attending attended at least one of the two sessions, how many of the people attended the morning session only?
a. ¾ attended both sessions
b. 7/8 attended the afternoon session

Rows:
MORNING / NO MORNING / total

Columns:
AFTERNOON
NO AFTERNOON
total

at the start of the problem, you have a total of 128 in the bottom right square, as well as '0' in the middle square (the square for "no morning, no afternoon"). if you didn't get the grid to work, this boldfaced part is probably where you went wrong.

takeaway: if a double set problem said something like "everyone did either A or B or both", or "no one did neither", then you need to put '0' in the "neither" square of the grid.

this problem is solved with the double set matrix elsewhere on this forum:
post34941.html#p34941


----------------

2]If 75 percent of the guests at a certain banquet ordered dessert, what percent of the guests ordered coffee?
(1) 60 percent of the guests who ordered dessert also ordered coffee.
(2) 90 percent of the guests who ordered coffee also ordered dessert.

could you please start a new thread for this problem? if you do, then i (or one of the other moderators) will detail the solution using the double set matrix. i don't want to show the whole solution here, since this problem is not the focus of the current thread.

3) Last year in a group of 30 businesses, 21 reported a net profit and
15 had investments in foreign markets. How many of the businesses
did not report a net profit nor invest in foreign markets last year?

(1) last year 12 of the 30 businesses reported a net profit and had investments in foreign markets.
(2) last year 24 of the 30 businesses reported a net profit or invested in
foreign markets, or both.
--------------------

same thing here -- please start a new thread with this problem as the focus of the thread.

i'll thank you to note that our forum rules prohibit posting multiple problems in the same thread, so this re-posting is also required by our rules.
we are not just trying to be martinets here -- the main purpose of the forum is to be a searchable archive of our input on these problems. if problems are posted in threads of which they are not the main focus, then no one will ever find them again in future searches.

... and, as noted above, please don't bump threads.

thanks for your cooperation.

[shadangi]

if there are 2 overlapping criteria, then use the matrix.
if there are 3 overlapping criteria, then use a venn diagram.
that's it.

do not EVER use a venn diagram to solve problems with 2 overlapping criteria, unless you like to make things harder than they should be.

Ron,
Thanks for the tip. I used to used venn diagram for everything, but lately I use matrix for everything. Is it possible for you give some quick example to illustrate when you think is the MOST efficient to use venn and when to use matrix ? If you can just put a mini example that you can create from the top of your head real quick? I certainly don't want to take too much of your time.
Thanks again.

EDIT: I went through some the links from above (I didn't realize there are 2 pages in this thread), and I was able to make the generalization. So the take-away is: If space within the 2 circles in the Venn Diagram is the complete set then Venn Diagram is easy, otherwise Double Matrix. Extrapolating this idea for 3 mutually exclusive overlapping sets (given space outside these sets is NOT allowed), Venn Diagram is easier to visualize. Please correct me if Ron or other instructors have more to add.

Thanks.

[RonPurewal]

if there are 2 overlapping criteria, then use the matrix.
if there are 3 overlapping criteria, then use a venn diagram.
that's it.

do not EVER use a venn diagram to solve problems with 2 overlapping criteria, unless you like to make things harder than they should be.

Ron,
Thanks for the tip. I used to used venn diagram for everything, but lately I use matrix for everything. Is it possible for you give some quick example to illustrate when you think is the MOST efficient to use venn and when to use matrix ? If you can just put a mini example that you can create from the top of your head real quick? I certainly don't want to take too much of your time.
Thanks again.

EDIT: I went through some the links from above (I didn't realize there are 2 pages in this thread), and I was able to make the generalization. So the take-away is: If space within the 2 circles in the Venn Diagram is the complete set then Venn Diagram is easy, otherwise Double Matrix. Extrapolating this idea for 3 mutually exclusive overlapping sets (given space outside these sets is NOT allowed), Venn Diagram is easier to visualize. Please correct me if Ron or other instructors have more to add.

Thanks.

this isn't the right way to think about the situation.
the right way to think about the situation is "just try something; if it doesn't work, then quit and try something else."

you really don't want to saddle yourself with excess layers of deliberation and over-thinking. just shoot first and ask questions later, as the saying goes.
i would always recommend trying the matrix first (unless there are 3 overlapping sets, in which case there is no matrix and the venn diagram is the only viable option).

[shadangi]

if there are 2 overlapping criteria, then use the matrix.
if there are 3 overlapping criteria, then use a venn diagram.
that's it.

do not EVER use a venn diagram to solve problems with 2 overlapping criteria, unless you like to make things harder than they should be.

Ron,
Thanks for the tip. I used to used venn diagram for everything, but lately I use matrix for everything. Is it possible for you give some quick example to illustrate when you think is the MOST efficient to use venn and when to use matrix ? If you can just put a mini example that you can create from the top of your head real quick? I certainly don't want to take too much of your time.
Thanks again.

EDIT: I went through some the links from above (I didn't realize there are 2 pages in this thread), and I was able to make the generalization. So the take-away is: If space within the 2 circles in the Venn Diagram is the complete set then Venn Diagram is easy, otherwise Double Matrix. Extrapolating this idea for 3 mutually exclusive overlapping sets (given space outside these sets is NOT allowed), Venn Diagram is easier to visualize. Please correct me if Ron or other instructors have more to add.

Thanks.

this isn't the right way to think about the situation.
the right way to think about the situation is "just try something; if it doesn't work, then quit and try something else."

you really don't want to saddle yourself with excess layers of deliberation and over-thinking. just shoot first and ask questions later, as the saying goes.
i would always recommend trying the matrix first (unless there are 3 overlapping sets, in which case there is no matrix and the venn diagram is the only viable option).

Thanks Ron. That makes perfect sense. If one knows what this matix means exactly, there isn't much of a difference b/w venn or matix. Just that matrix make the problem more mathematical and hence easier to solve in most circumstance. However, venn is no different but more conceptual - if one is not very comfortable he/she can get lost in the connotations.

[jnelson0612]

Great discussion everyone!