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 From categories: All categories Discussion Forum: Generic questions Discussion Forum: Subject Questions

0.33 seems right according to that logic, and 0.5 seems right according to this. Obviously both cannot be right so I am making some wrong assumption somewhere, or maybe I have misinterpreted the question?

Also, can you explain the importance of the phrase 'at least' as mentioned in the second question in the wikipedia article? I do not understand the wrong assumptions that have been made based on that…

I'ts nicer to study probability like this than from the textbook :)

by , 05 Mar 2014 14:07

Your question is like the first case in the link, right? See, I don't understand why the initial answer I gave is wrong. Even if you look at it differently, you get 0.5.
So you have 4 different options - BB, BG, GB, and GG. It is definitely not GG because you have already picked a boy so it is between BG, GB, and BB but it is not equal probability between all three. In BB, you have an increased probability of picking a boy in the first place since there are two of them to chose from rather than just one, as in the other 2 cases; so the actual options are BB, BB, GB and BG which again gives you 0.5 for the other person to also be a boy.

by , 05 Mar 2014 14:06

I agree, counter intuitive questions do bring a new curiosity to learn. It will be a value add if you give complete explanations or related resources to your questions.

• Arctic thing is wrong as you pointed out, so better take it off.
• Candle experiment might need a new post itself.
• I do not think the exponent thing is counterintuitive. You might like to use the fact
(1)
\begin{align} 2^0+2^1+\dots +2^n=2^{n+1}-1 \end{align}
by talegari (guest), 03 Mar 2014 13:04
Nithila (guest) 02 Mar 2014 16:22
in discussion Discussion Forum / Subject Questions » A question on probability

The 4 possibilities (in order of picking) are MM, MF, FM, or FF. FF and FM are not considered because you pick a male first. So it is between MF and MM. After picking the first male, whose probability is 1 because you have done it, there is equal chance of the other person being a male or a female which is 0.5 each. So the probability that the other person is a male is (1 x 0.5) = 0.5

by Nithila (guest), 02 Mar 2014 16:22

There are two people one older than the other. You pick a male. What is the probability of the other person being a male?

A question on probability by , 02 Mar 2014 10:04

Looks like melting of arctic ice caps will also increase sea level.

http://nsidc.org/news/press/20050801_floatingice.html

by , 01 Mar 2014 22:30
Nithila (guest) 01 Mar 2014 14:26
in discussion Discussion Forum / Subject Questions » Test for calcium ions

Ok, got it.

by Nithila (guest), 01 Mar 2014 14:26
01 Mar 2014 13:29
in discussion Discussion Forum / Subject Questions » Test for calcium ions

Na is more reactive than Ca which means Ca2+ is more reactive than Na+. Read the print out of electrochemical series I have given in the class. I remember explaining this in the class with reference to why Zn will not react with cold NaOH but Zn2+ will.

Re: Test for calcium ions by , 01 Mar 2014 13:29
Nithila (guest) 01 Mar 2014 12:49
in discussion Discussion Forum / Subject Questions » Test for calcium ions

Why does Ca2+ replaces Na+ in NaOH to give Ca(OH)2? Na2+ gets reduced more readily than Ca2+, but there is no reduction happening here because the oppositely charged ions (Ca2+ and OH-) attract each other and bond, right? But anyway, why does Na+ get replaced?

Test for calcium ions by Nithila (guest), 01 Mar 2014 12:49
kalnanmaga (guest) 20 Feb 2014 14:32
in discussion Discussion Forum / Generic questions » trial question

no, it is a fullerene ball :)

by kalnanmaga (guest), 20 Feb 2014 14:32
20 Feb 2014 14:26
in discussion Discussion Forum / Generic questions » trial question

here is a trial question: why is benzene a ring?

trial question by , 20 Feb 2014 14:26