Brain Teasers
Missing Marbles
Deepsea was walking to her computer when she lost her marbles. They fell out of the bag and rolled under the couch.
Deepsea has 3 times as many green marbles as blue marbles, and 5 more red marbles than green marbles. The total number of marbles is the number of red marbles plus 4 times the number of green marbles.
Deepsea reaches her hand under the couch. She pulls something out. She knows it's a marble but doesn't know what color. What is the probability of it being a blue marble?
Deepsea has 3 times as many green marbles as blue marbles, and 5 more red marbles than green marbles. The total number of marbles is the number of red marbles plus 4 times the number of green marbles.
Deepsea reaches her hand under the couch. She pulls something out. She knows it's a marble but doesn't know what color. What is the probability of it being a blue marble?
Hint
It's lower than the chances of it being a red marble.Answer
Zero!Deepsea only has 5 red marbles.
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Comments
whoops i didnt get it oh well very good teaser you got me very cool congratulations you trickster you!
Hehe, this was a great one. It wasn't very hard, since it was in the Trick category, but if it wasn't then I wouldn't have been tipped off. Good work
I couldn't find ou9t how many she had so I checkecx the answer...then I saw the category, nice one
i thot i wouldnt get this 1 even tho im pretty good at math but when i looked back it took like 2 seconds...it was so easy but i enjoyed it!
cute.. the number of red marbles plus nada.. I liked it.
Very good trick. I also thought the trick could be that she had other marbles not accounted for, as the question didn't say whether the marbles stated were her ONLY marbles... Here's my crazy math explanation:
x= blue marbles
3x= green marbles
3x + 5= red marbles
y= other color marbles
Adding these together we get 7x+5+y marbles
The total marbles are 4 times green (12x) plus the number of red (3x+5), making 15x+5
Thus, 7x+5+y=15x+5
Simplifies, this becomes y=8x
It doesn't matter what x is, as the final probability is the same, so I'll make it x=1
Here's the marbles we have now:
blue=x=1
green=3x=3
red=3x=5=8
other=y=8
If other marbles were present there'd be a multiple of 20 marbles under the couch, making the probability of getting a blue marble 1:20.
If there's no other colors, of course the answer would be that there was only the 5 red marbles, as you stated!
Do I have too much free time?
x= blue marbles
3x= green marbles
3x + 5= red marbles
y= other color marbles
Adding these together we get 7x+5+y marbles
The total marbles are 4 times green (12x) plus the number of red (3x+5), making 15x+5
Thus, 7x+5+y=15x+5
Simplifies, this becomes y=8x
It doesn't matter what x is, as the final probability is the same, so I'll make it x=1
Here's the marbles we have now:
blue=x=1
green=3x=3
red=3x=5=8
other=y=8
If other marbles were present there'd be a multiple of 20 marbles under the couch, making the probability of getting a blue marble 1:20.
If there's no other colors, of course the answer would be that there was only the 5 red marbles, as you stated!
Do I have too much free time?
easy! got it right away, but it was a good one! i mean if it was hard and i didnt get it then i would feel stupid, so keep the easy ones comin.
i thought the probability of getting the blue marble is 1:20 but i was wrong.good one,you got me.
to me it was incredibly easy i didnt have to do the math
but nice one though if u would have saw trick that would hav gav it away
but nice one though if u would have saw trick that would hav gav it away
I didn't get it...
she didnt have any blue marbles! easy, but good teaser!
Oct 03, 2005
This is misleading. You say Deepsea HAD 4 times more blue or whatever. But, if she (he?) doesn't have ANY blue marbles, then this is ... well... a lie!
not really 4 times 0 is 0
hey onlyeeyore, i think you do have too much free time!! lol j/k. i would have done the same thing if i had half a brain for math... but, good teaser!! keep them coming and i will try again!!
almost got me,,,had to read this one twice!
nice job
nice job
and to answer onlyeeyore,,,,YES!
I would have actually used paper to solve this one, but I'm in very advanced math and am sick of math in general. Excellent, tho.
YES, eeyore, you do have too much free time, but i suppose if i read this a week ago, I would have done the same thing.
YES, eeyore, you do have too much free time, but i suppose if i read this a week ago, I would have done the same thing.
tat was cool but u should have added more
I loved AND i got it right. Yay, go me!!! BTW, I had to laugh out loud at that 1st sentence. That was hilarious!!!!
x=blue marbles
3x=green marbles
3x+5=red marbles
7x+5=total marbles also stated as red plus 4xgreen which is 3x+5+4(3x)=3x+5+12x or 15x+5 therefore
7x+5=15x+5
7x=15x which is impossible unless as Deepsea pointed out x=0 simple Yes????
3x=green marbles
3x+5=red marbles
7x+5=total marbles also stated as red plus 4xgreen which is 3x+5+4(3x)=3x+5+12x or 15x+5 therefore
7x+5=15x+5
7x=15x which is impossible unless as Deepsea pointed out x=0 simple Yes????
You get that onlyeeyore???
too many emoticons???????
You cant be serious!!!!!!!!!!!!
too many emoticons???????
You cant be serious!!!!!!!!!!!!
Kee hee I actually got this one, I am so proud!!
This was very tricky, Nice bit of imagination making this one.
I like that one.
**ahem**
7x=15x can be factored down to:
0=8x
THUS
x=0
I liked this one!
7x=15x can be factored down to:
0=8x
THUS
x=0
I liked this one!
I guess deepsea lost her marbles. hehehehe.
2 ways to read this:
total = (red + 4)*green
total = red + 4*green
didn't like how it was worded...
total = (red + 4)*green
total = red + 4*green
didn't like how it was worded...
You're right. I should edit that.
I liked it.
The only thing was it stated that she knew it was a marble but not what color. Surely she would know if they were all the same??
Asides from that a thumbs up from me
The only thing was it stated that she knew it was a marble but not what color. Surely she would know if they were all the same??
Asides from that a thumbs up from me
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