## Sunday, April 17, 2005

### Feel Like Twisting Your Brain?

I have got two questions here to twist your brain, if you feel like life is nothing more than boring routines.

1. Safe sex

There are 2 guys and 2 girls. The 2 guys want to fuck the 2 girls (ie each guy screws both girls) but there is a problem ... There are only two condoms available. Use the condoms any way you want - reuse, flip it, etc - but you cannot wash it.

No body fluids can be exchanged (even girl-girl or guy-guy exchanges), else the sex would not be considered safe from STDs.

How can the task be done?

2. The Chance?

Suppose it is assumed that about 5% of the general population use drugs. You employ a test that is 95% accurate, which we’ll say means that if the individual is a user, the test will be positive 95% of the time, and if the individual is a nonuser, the test will be negative 95% of the time. A person is selected randomly and given the test. It is positive. What does such a result suggest? Would you conclude that the individual is highly likely to be a drug user?

4 PHD got the answer wrong when they wrote their answer to the newspaper, a similar question like this was directed to a group of experienced doctor and only 2 doctors (8%) got the correct answers.

From ReCom

Have fun!

Eric Fu said...

I hate to say it, but the second question reminds me about my nightmare with my probability course - a field that I dislike in mathematics. =)

day-dreamer said...

so when are the answers gonna come out??

i'm waiting... :P

Ren Jie said...

Haha, i'm waiting for the answer for the first question *evil laugh* :p
Erm, heard someone saying that the first guy will use two condoms, and something like that, but still can't really think of the right answer.
So, waiting for the answers, hehehe!

youngyew said...

Just try first larr.. I will provide the answers a few days later. There's always more satisfaction if you manage to think of the answers yourself.

Eric: Hmm... I can empathize. Just some question for everyone to ponder: Can interest be cultivated?

p/s: If you want the answers immediately, follow the link in the passage to the Singaporean blog and ReCom. The answers are all there.

day-dreamer said...

I hereby announce that my Thinking Cap is now torn! Who can find a tailor or whoever to fix it?

After thinking and thinking (but maybe not that much of thinking anyway), i have come up with several answers for Q1 which i feel is not so acceptable after all.

1. both guys don't screw up either girls

2. don't ejaculate.

3. use the condom twice.

correct ah, doctor?

as for Q2, doctors also can't answer it. how can i?

Anonymous said...

oh well....
hm...Lets say....the 2 guys are A n B..n the 2 girls are C and D..

now....gv A n B a condom each

A fuck C, B fuck D...
take off the condoms bofore they ejaculate....

then A uses B's condom to fuck D.....
and B uses A's condom to fuck C....

there is not exchange of fluid between the two girls since for both rounds, the condom used is the same for each of the girls.

However...this is assuming that these 2 guys hv no pre-cum.....

rather disgusting dude....hehe...:p

StanleyYP

youngyew said...

No, no, unfortunately day-dreamers and Stanley gave the incorrect answer...