Riddle #237

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logicmathclean

Consider the following explanation for why 1=2: 1. Start out Let y = x 2. Multiply through by x xy = x2 3. Subtract y2 from each side xy - y2 = x2 - y2 4. Factor each side y(x-y) = (x+y)(x-y) 5. Divide both sides by (x-y) y = x+y 6. Divide both sides by y y/y = x/y + y/y 7. And so... 1 = x/y + 1 8. Since x=y, x/y = 1 1 = 1 + 1 8. And so... 1 = 2 How is this possible?
Step 5 is invalid, because we are dividing by (x-y), and since x=y, we are thus dividing by 0. This is an invalid mathematical operation (division by 0), and so by not followinng basic mathematical rules, we are able to get strange results like these.
83.67 %
51 votes
logicmathtricky

A train leaves from Halifax, Nova Scotia heading towards Vancouver, British Columbia at 120 km/h. Three hours later, a train leaves Vancouver heading towards Halifax at 180 km/h. Assume there's exactly 6000 kilometers between Vancouver and Halifax. When they meet, which train is closer to Halifax?
Both trains would be at the same spot when they meet therefore they are both equally close to Halifax.
81.65 %
45 votes
logicmathcleantricky

You have a sock drawer. It has 4 black socks, 8 brown socks, 2 white socks and 8 tan socks. You need to pull out a matching pair of socks in the dark. There is no light and you couldn't see the socks. How many socks you should pull out in the dark to get one matching pair of socks?
Five. You have only four different colors of socks. If you pick 5, you can surely get one pair of matching socks.
81.55 %
59 votes
cleanlogicmathsimple

Create a number using only the digits 4,4,3,3,2,2,1 and 1. So I can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits.
41312432.
81.36 %
72 votes
mathcleansimplelogic

Count the number of times the letter "F" appears in the following paragraph: FAY FRIED FIFTY POUNDS OF SALTED FISH AND THREE POUNDS OF DRY FENNEL FOR DINNER FOR FORTY MEMBERS OF HER FATHER'S FAMILY.
It appears 14 times. Make sure to count the "F"s in the word "OF", which people commonly miss.
81.26 %
44 votes
cleanlogicmath

A 400 yard long train, travelling at 30 mph, enters a 4.5 mile long tunnel. How long will elapse between the moment the front of the train enters the tunnel and the moment the end of the train clears the tunnel?
9 minutes and 27.2727 seconds.
81.26 %
44 votes