Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

If a single MBP has a 50% probability of being flawless and you purchase two of them, what is the

Hieveryone

Hieveryone

macrumors 603
Original poster
Apr 11, 2014
5,627
2,339
USA
combined probability both will be flawless, and the combined probability both will be flawed?

Let's say they each have a 50% chance of being flawed or flawless.

Sorry it's an odd question, but I was curious what the answer was. I'm arguing this with a friend right now.
 
Last edited:
Hieveryone said:
you bought 2 of them? Let's say they each have a 50% chance of being flawed or flawless.

Sorry it's an odd question, but I was curious what the answer was. I'm arguing this with a friend right now.
Click to expand...

.5*.5 = .25 assuming just a binary flawed or not, so the probability that one of the two would have a flaw would be 75%.

But the probabilities of a flawed MacBook Pro are much lower than that, and it's far more complicated than that as well. You'd have to take into account variable factors of failure rates/components, and look at different hardware configurations, etc....
 
  • Like
Reactions: Hieveryone
smallcoffee said:
.5*.5 = .25 assuming just a binary flawed or not, so the probability that one of the two would have a flaw would be 75%.
Click to expand...

THANK YOU!!!! I got it right but saw it wrong, meaning interpreted the numbers wrong. But at least the math I did and the method I did was right.
 
The thread title asks about the chance of "it" being flawless. That's still 50% no matter how many you buy. If you wanted another answer you should have asked about the chance of both being flawless.
 
  • Like
Reactions: old-wiz, bevsb2 and DeltaMac
And - your math actually is wrong.
Quantity doesn't change the probability on each unit.
With your original assertion that there's a 50% chance of a fault, then each one that you buy has that same 50% shot at greatness.
Buy 20, you still have 50% chance of faults on each one.
(Buying units in quantity won't lessen your chance of any individual unit having a fault.)
 
  • Like
Reactions: Jaro65, old-wiz and chabig
DeltaMac said:
And - your math actually is wrong.
Quantity doesn't change the probability on each unit.
With your original assertion that there's a 50% chance of a fault, then each one that you buy has that same 50% shot at greatness.
Buy 20, you still have 50% chance of faults on each one.
(Buying units in quantity won't lessen your chance of any individual unit having a fault.)
Click to expand...

The OP asked about the probability for two of them, not each individually. The probability for any given combination will be 1/4.

Just like a coin, you have the following possibilities {T/T, T/F, F/T, F/F}. The probability of having one with a failure is therefore 3/4, or .75.
 
  • Like
Reactions: KayM8 and Hieveryone
smallcoffee said:
The OP asked about the probability for two of them, not each individually. The probability for any given combination will be 1/4.

Just like a coin, you have the following possibilities {T/T, T/F, F/T, F/F}. The probability of having one with a failure is therefore 3/4, or .75.
Click to expand...

YES! The probability for 2 of them NOT individually. If you count the chance of any one being flawless or flawed, it's 50% no matter how many you buy I think!
 
Yep
Probability is easiest to mis-interpret, particularly if you don't consider sets correctly, or miss that "sets" are not the key factor, and you get to remember that individual units can decide the result (not the set)
 
Hieveryone said:
Wait, what's wrong with the title?
Click to expand...
See post #5. Your title asks about "it" which is a singular pronoun.

The title should say, "If a single MBP has a 50% probability of being flawless and you purchase two of them, what is the combined probability that both will be flawless."
 
Hieveryone said:
you bought 2 of them? Let's say they each have a 50% chance of being flawed or flawless.

Sorry it's an odd question, but I was curious what the answer was. I'm arguing this with a friend right now.
Click to expand...
What's with the run on thread title that just cuts off?
 
chabig said:
See post #5. Your title asks about "it" which is a singular pronoun.

The title should say, "If a single MBP has a 50% probability of being flawless and you purchase two of them, what is the combined probability that both will be flawless."
Click to expand...

I changed it up and added some as well!
[doublepost=1489985098][/doublepost]
C DM said:
What's with the run on thread title that just cuts off?
Click to expand...

It doesnt' fit!
 
Hieveryone said:
How could I ahve made it shorter?
Click to expand...
Create a title for what the thread is about and ask the actual questions and provide details in the thread itself? Let's say something along the lines of "Probability of flawless MBPs" for the title perhaps.
 
Don't people go to school anymore? o_O I thought that basic combinatorics was a mandatory subject?
 
  • Like
Reactions: DeltaMac
leman said:
Don't people go to school anymore? o_O I thought that basic combinatorics was a mandatory subject?
Click to expand...
Haha. This probably came up in high school math somewhere, but I didn't actually get a class in probabilities until college. And even then, I don't think it was compulsory for everyone. But yeah, it's still a rather easy question for anyone who's placed a wager, even a little. Yes, the US school system is not very good, and it will likely get worse (speaking of my experience, not OP's).
 
maflynn said:
Agreed, I think Macs still well made and the risk of getting a defect is rather low.
Click to expand...

Yeah. In general most computers are made pretty well. Especially now where we have reduce the number of moving components to at or near 0. There just isn't much there to be broken. With battery swaps possible, you could hang on to a new 2016 MacBook Pro for 5-8 years I think.

The main issue with windows pcs is the operating system, not the hardware.
 
Guys...seriously?

The probability of each unit being flawless, in OP's scenario, is 50%, irregardless of how many bought. However, the PROBABILITY of buying two and having BOTH of them being flawless is (1/2)(1/2) = 25%
 
No offense but this is a classic click and bate thread title. It's thread titles like this that show people have too much free time and start making silly juvenile posts/threads. I see no benefit in this topic or way it can help others just silly banter.
 
  • Like
Reactions: HenryDJP
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back