Math Survey Question

[Zetta_x]

If you have 4 observations that have an average of 10 and the 5th observation is 20, what is the average of all the observations. Please spoiler your answers and answer in the poll

Poll closes in 3 days

 

[Sterling]

So all 4 observations average out to 10, with the addition of 20 because of the 5th observation? Or is it that I have 4 observations, each of which averages out to a 10 and the fifth on is 20.

Spoiler: My answer

12

Actually you'll get the same answer either way now that I think about it.

 

[Zetta_x]

Thanks for the responses so far
I'm trying to figure out different logical patterns that people take when coming up to a problem that may have not seen.

 

[FAST6191]

[Being a bastard]
Mean, median or mode?
[/being a bastard]

 

[Zetta_x]

I'm so glad you have mentioned that. I honestly predicted that if I were to say mean, it would blow over most people's heads. Mean is a very picky term that I feel the average would not be able to pick up one (so the mean)

 

[Foxi4]

That's actually pretty easy...

Spoiler

Regardless of the constituents, we know that the first 4 draws average to 10. Knowing that, we can replace our unknown numbers with 10 and sum them all up - the sum would be exactly the same regardless of constituents. 10*4 = 40. The 5th draw gives us the number 20, so we add that and the sum is now 60. Divide that by the amount of draws, which is now 5, and you get 12.

 

[gifi4]

Simple.

Spoiler

4 multiplied by 10 gives you 40, considering there's only 4 pieces of data, divide by 4. That leaves you with 10. Add the 20 in as a 5th piece of data and you get a total of 60 divided by 5(Each piece of data) and you end up with 12.

 

[Issac]

Spoiler

10 = x/4 <=> 40 = x
(x+20)/5 = 60/5 = 12

Quite easy indeed. However, I got 39 / 36 on my statistics and probability exam. (not a typo)

 

[Vulpes Abnocto]

Spoiler

The anomalous observation is due to a mis-calibration in your equipment.
The answer is 10.

 

[Zetta_x]

I teach a statistics class and I shit you not, someone had put an average greater than the maximum value.

 

[Maxternal]

dang it, I just answered randomly before I saw there was actually a question in the op

 

[marcus134]

Spoiler

Both 10 and 12 can be correct, it simply depends on the distribution and how far is the fifth observation compared to 4 preceding one.

 

[Alexrose]

Spoiler

0.2(40+20)=12.

This is literally primary school maths; why are you acting like we should spoiler this stuff?

 

[Zetta_x]

Spoiler

0.2(40+20)=12.

This is literally primary school maths; why are you acting like we should spoiler this stuff?

Alex, the purpose is that every vote is independent. If you show your answer, the votes have dependence amongst them. Do you know the definition of what it means for each observation to be uncorrelated?

There once was a post on facebook with elementary math (the one that had the order of operations). I think as much as 1/3 to 1/2 half got it wrong.

Thank you for being a douchebag and not put spoiler tags when you clearly see that I have asked to do so.

---

The logical step that people will miss is how you got 40. A few people look like they just took the average between 20 and 10 which is 15.

Tl;dr the arithmetic was designed to be easy, but it was not a test of arithmetic, it was a test of logic and problem solving.

 

[Tom]

Are we just doing your HW?

 

[Sterling]

Are we just doing your HW?

No, he's a statistics teacher. If you'd read the topic, you'd figure that out. Even if it was his homework, he wouldn't have asked us a single question this simple.

 

[Tom]

No, he's a statistics teacher. If you'd read the topic, you'd figure that out. Even if it was his homework, he wouldn't have asked us a single question this simple.

It doesn't say that in the topic, Looking at his profile you see it, not on the topic

 

[Coto]

If you have 4 observations that have an average of 10 and the 5th observation is 20, what is the average of all the observations. Please spoiler your answers and answer in the poll

Spoiler

4 obs being 10 of average each one means 40, then 20 because of the fifth one, divided by the resulting number of observations in total (5)

40+20/5= 12

Or

Spoiler

4 obs resulting in average of 10 in total (each would be something like 2,5) then the fifth one resulting in average of 20. Then

(average) / (divided by number of observations in total)

20+10=30/5=6

That is, considering basis of 10 as total for every observation, or 40, being 10 for each observation, then simply adding the fifth observation, and its valuew

 

[Sterling]

It doesn't say that in the topic, Looking at his profile you see it, not on the topic

I teach a statistics class and I shit you not, someone had put an average greater than the maximum value.

This says otherwise. >.>

 

[Saken]

Spoiler

You are taking observations, therefore omit the 20 value as outlier. "Average" is then 10 (40/4)