why did sigmund frued come up with the 7% solution?
479346
The seven-per-cent solution is actually a fictional novel published in 1976 that stars Sigmund Freud as a character.
380004
I don't understand.  Can you explain the problem a little better?
194129
1-.42^7=0.99769460666752\n\nboris had the right idea but made an arithmetic error.
123413
adams got the right idea.
231498
In total the dude made 9000, which is not quite a lot to be honest for me. (I spend too much). Anyway!\n\nSay the amount he invested at 7% is X, this would naturally make the rest 9000-X, right? Good.\n\nSo hee is the math!\n\n0.07*X + 0.1(9000-X)=720 ....... clear! Now for simplicity, multiply all by 100 and you will get:\n\n7X + 10(9000-X) = 72000 ... and after distribution:\n7X + 90,000-10X = 72000\n-3X = 72,000-90,000 = -18,000  \nX = -18,000/-3= 6,000\n\nSo this is the amount he invested at 7% and the rest, as we shwed earlier, is 9,000-X = 9,000-6000 = 3,000\n\nSo he invested $3,000 at 10%.\n\nOf course you know this is true if the interest was made in one year and without talking taxes, which would be anouther story.
73252
7, is scientifically correct...
583994
I would think everyone knows how to get it right, but explaining why the given calculation is wrong is what we are interested. \n\nThe key here is that £2 came from the £27.  So there is no  way you add £2 to the £27 again!
1133537
7 is not a perfect number.
117935
I believe that it is 7... If the concentration of the acid and base are equal then they would probably neutralize the solution.
423596
1/14 X 100% = 7%\n\nu r right
802410
rfamilymember is right and so is his method for getting the answer. It's $113.33\n\nJust multiply this by 0.075 to check. (That's 7.5 hundredths, in other words,7.5 per cent.)
958556
Answerer #1 is absolutely right, but you could have looked it up in Wikipedia in 30 seconds and saved the points.
57610
The first theoretical calculation seems to have been carried out by Archimedes of Syracuse (287-212 BC). He obtained the approximation \n\n223/71 < π < 22/7. \n\nBefore giving an indication of his proof, notice that very considerable sophistication involved in the use of inequalities here. Archimedes knew, what so many people to this day do not, that π does not equal 22/7, and made no claim to have discovered the exact value. If we take his best estimate as the average of his two bounds we obtain 3.1418, an error of about 0.0002.π \n\nHow is Archimedes' Arguments, you could see on the link below ( 1st link).\n\nHowever, scientists using computer to get the walue of pi today(look 2nd link).
981458
50000/140000 x 100 = 35.7%
426667
I worked with 1,000 holders, just to get rid of some of the decimal points.  Out of 1,000 holders, 500 would be made by System A.  Of those 500, 15 will be defective.  System B makes 300, 12 of which will be defective; System C makes 200, 10 of which will be defective.  Out of every 1,000 holders, 37 will be defective and 15 of those 37 defectives will be made by System A.  15 divided by 37 is 40.54%.  I agree with your answer! :D
303107
as usual more than it was worth to find a peaceful solution
379145
Look up Gauss. Story is he added up 1..100 in grade school and invented the n*(N+1)/2.