The conditions were to place a different number in each of the nine cells so that the three rows,three columns, and two diagonals should each add up 15. Probably the reader at first set himself an impossible task through reading into these conditions something which is not there—a common error in puzzle-solving. If I had said "a different figure," instead of "a different number," it would have been quite impossible with the 8 placed anywhere but in a corner. And it would have been equally impossible if I had said "a different whole number." But a number may, of course, be fractional, and therein lies the secret of the puzzle. The arrangement shown in the figure will be found to comply exactly with the conditions: all the numbers are different, and the square adds up 15 in all the required eight ways.
First guy needs to sacrifice himself (Whether he lives or not depends on his luck).
The sole duty of the last person (to whom the question is asked 1st) needs to establish
the parity of the BLACK hats.
If there are even number of BLACK hats, he says BLACK, else he says RED.
(If his answer suits his hat colour, he lives. If not he dies).
Now the duty of the 2nd last person is to observe the parity of the BLACK hats.
If he finds even number of BLACK hats,it means that his hat colour is RED.
So he says RED & he lives.
Now, the 3rd last person needs to work a bit more hard.
He need to remember the previous 2 answers and analyse his hat.
As the last person said BLACK, it means there are even no. of BLACK hats at that stage.
As the 2nd last person said RED, it means that the no. of BLACK hats is still even.
If he finds odd no.of BLACK hats, his hat colour must be BLACK, else RED.
This procedure is followed by the remaining people till the 1st person. Thus the complexity
increases and hence they need to place themselves such that most intelligent person in 1st
place in the queue and the least intelligent person in the last place in the queue.
Thus a minimum of 19 members can be saved and if luck favours all of them can be saved.
Stage 1:
Seperate the coins into 3 stacks each with 9 coins (say A,B,C).
Measure stack A vs B (1) , if A=B then C will be the odd stack
else measure A vs C (2) if A=C then B is the odd stack.If A < or > C , A is the odd stack.
Thus in stage 1 we have done 2 measurements.
Stage 2:
Pick the odd stack and seperate into 3 more stacks each with 3 coins (say D,E,F).
Measure D vs E (3) , if D=E then F is the odd stack
else measure D vs F (4), if D=F then E is the odd stack. If D < or > F, then D is the odd stack.
Thus in stage 2 we have done 2 more measurements.Total 4.
Stage 3:
Pick the odd stack and let the 3 coins be G,H,I.
Measure G vs H (3) , if G=H then I is the odd stack
else measure G vs I (4), if G=I then H is the odd stack. If G < or > I, then G is the odd stack.
Thus in stage 3 we have done 2 more measurements.Total 6.
Therefore the answer is 6 number of weighings are required at minimum.
A lot of rumors have been going around about Google voice calls, but now we know it’s true! Google has just made it official today and they are working on it right now. Google’s demoed the “Call from Gmail” service for us in San Francisco this morning, and it’s looking like it’s not free, but fairly cheap, it’ll cost around $0.02 per minute. If you live in the US or Canada and are making calls to someone in the US or Canada, you won’t have to pay a fee because it’ll be free. Incoming calls pop up as a chat window in Gmail (and ring your Google Voice-equipped phones simultaneously).
To send an outgoing call you have to press the “call phone” button in the corner then type in the number. User’s can see the number and send them to voice mail with one tap on the screen. It’s a very simple calling system and easy to use and understand. You’ll be able to make calls to US and Canadian landlines completely free of charge, buying prepaid credits using Google Checkout for international landline calling at $0.02 a minute and up to $0.19 for calls to international mobile devices.
Google will sell its own credits for the program (via Google Checkout), which should be available in a few weeks, but the Voice in Gmail service goes live today in the US and will begin rolling out to users immediately.
