00:00Alex is a teenager living in New York City.
00:04His science teacher assigned him an interesting experiment, and Alex's mind was buzzing
00:09with possibilities.
00:11He ran home and found a huge watermelon in his mother's pantry.
00:15It was massive!
00:16When he weighed it, he found it was 100 pounds!
00:20He found out everything he needed about watermelons.
00:24The most important information was that watermelons were generally 99% water.
00:31For the experiment, he left the fruit drying out in the sun for a few days.
00:36With the help of a trusty weighing scale, he discovered that the watermelon was now
00:40only 98% water!
00:43To get a 10 in his science experiment, he needed to figure out the total weight of the
00:47watermelon after losing 1% of its water.
00:52Can you help Alex out with this one?
01:07Here's the deal.
01:08At first glance, this riddle sounds like a piece of cake.
01:11You might have guessed that the watermelon now weighed 99 pounds.
01:15But that's actually not even close!
01:18Let's work out the answer together.
01:20To solve the riddle, Alex should start by thinking about the non-water part of the watermelon.
01:26If the watermelon was 100 pounds and 99% water, then 1% of it was the actual fruit.
01:34So, 1% of 100 pounds is 1 pound of the fruit.
01:39After drying, the watermelon is 98% water, which means the 1 pound of fruit now makes
01:45up 2% of the total weight.
01:48So, if 1 pound is 2% of the total weight, we can call that total weight W.
01:551 pound of 2% of W, which is the same thing as saying that 1 pound equals 0.02 times W.
02:05To find W, we need to divide both sides by 0.02.
02:11So, if W equals 1 pound divided by 0.02, this means that W equals 50 pounds.
02:20Eureka!
02:21Alex had cracked the case!
02:23The once-100-pound watermelon now weighed 50 pounds!
02:30Cole invited his girlfriend Nikki over for a game night at his place.
02:35He told her he had a very difficult quiz prepared for her to solve.
02:40Cole showed her an empty triangular glass.
02:44He grabbed some orange juice and asked her when the glass would be closest to full.
02:49Measuring from the bottom of the glass to the top, Nikki had to guess the percentage
02:53of orange juice she'd have to pour in order for the triangular glass to be the closest
02:58as possible to half full.
03:01If you had to guess without any calculations, what would you say?
03:10This is tricky, but let's check out the answer.
03:17Intuitively, you might have thought that the answer was 50% of the height of the glass,
03:24but that's wrong.
03:25When 50% of its height is filled, it means there's only 12.5% of juice inside the glass.
03:33In a similar way, if the triangular glass was filled up to 70% of its height, this would
03:39mean that it is only 34.3% full.
03:44The answer we're looking for is 80% of the height of the glass.
03:49To solve this riddle, we need to remember a basic geometry formula that says that the
03:53percentage of the volume is equal to the cube of the percentage of the height.
03:58So, if we're looking for 50% of the volume, we're searching for nearly 80% of the height
04:05to make it equal.
04:07Got it, genius?
04:10It was a sunny day in Los Angeles, and Harry and Maria were planning their wedding.
04:16Maria was very nervous because she couldn't figure out the seating chart for their wedding.
04:22They had a hundred guests and had to distribute them around.
04:26To lighten up the mood, Harry remembered an old, difficult-to-solve riddle that would
04:30definitely take Maria's mind off things.
04:34He asked her if she could figure out the mathematical equation needed to get the number
04:39100 out of four nines.
04:42She could use the simple things such as addition, subtraction, division, and multiplication.
04:48The important part was that she got the number 100 out of it all.
04:51Can you help Maria out?
05:03The best way to solve these kinds of riddles is to start backwards.
05:07There are multiple ways to get the total of 100.
05:10Dare to join me in brainstorming the ways?
05:14You could simply add 99 plus 1, or 90 plus 9 plus 1.
05:18But that's not what the rules ask us to do.
05:21We need to use the number 9 four times.
05:25For example, 90 plus 9 times 9 divided by 9, well, this won't get us to 100.
05:33But what about 99 plus 9 divided by 9?
05:38I know we have two nines as one number, but that's okay by the rules.
05:42This way, you use all the four nines you need to use, although you are combining two nines
05:47into one number.
05:50But there are other possible answers.
05:52What do you say?
05:54Did you find any other answers to this crazy riddle?
05:59Once upon a time in a far away kingdom, Queen Matilda needed to hire a worker for a seven
06:04day project.
06:05The job was crucial, and she wanted to ensure the worker was paid daily.
06:10However, she could only pay him in gold bars, and she could only make a minimum of two cuts
06:16in her precious gold bar.
06:19Her plan was to pay him one seventh of the bar per day.
06:23Can you figure out how she could manage to do this, following the conditions we showed?
06:38Well, Queen Matilda is a very intelligent woman, so this is how she worked it out.
06:44She made two precise cuts in the gold bar, creating three pieces.
06:49The first piece was one seventh of the bar.
06:51The second piece was two sevenths, and the third piece was four sevenths.
06:58On the first day, the worker finished his shift, and Queen Matilda handed him the one
07:02seventh piece.
07:05On the second day, she swapped the one seventh piece for the two sevenths piece, so the worker
07:10now had two sevenths of the bar.
07:15By the third day, she gave him back the one seventh piece, resulting in the worker having
07:19three sevenths in total.
07:22On the fourth day, Queen Matilda took back the one seventh and two seventh pieces and
07:27handed over the larger four sevenths piece.
07:32On the fifth day, the Queen handed over the one seventh piece again, so the worker now
07:36had five sevenths of the bar.
07:39On the sixth day, the Queen took back the one seventh piece and gave him the two sevenths
07:44piece, resulting in the worker having six sevenths of the bar.
07:49Finally, on the seventh day, the Queen handed over the last one seventh piece, completing
07:54the full bar payment.
07:57And that's how Queen Matilda managed to pay her worker every day with just two cuts in
08:02the gold bar.
08:03Brilliant, right?
08:05Way to go, Queen M!
08:09Jake is on a bus, heading to visit his parents for the weekend.
08:13On another bus, coming from the opposite direction, is his brother, Max.
08:20Both buses are barreling down the road towards each other, each cruising along at 40 miles
08:25per hour.
08:26They started out at 40 miles apart.
08:29The brothers have been texting each other about their journeys, eager for the family
08:32reunion.
08:34As Jake stares out the window, he notices a little bird flitting around.
08:39His mind starts to wander, and he imagines the bird flying back and forth between the
08:43two buses, and wonders how many miles the birds would have flown back and forth until
08:48the buses meet each other.
08:50Can you help him out there?
09:01First, Jake figures out how long it will take for the buses to meet.
09:06Since both buses are driving at 40 miles per hour, their combined speed is 80 miles
09:11per hour.
09:12With the 40-mile distance between them, he divides the distance by their combined speed.
09:1840 divided by 80 equals 0.5 hours, or 30 minutes.
09:25Next, Jake turns his attention to the bird.
09:29He guesses the bird is flying at 50 miles per hour.
09:33Jake quickly multiplies the bird's speed by the time it takes for the buses to meet.
09:38This equals 25 minutes.
09:42So by the time the buses meet, the little bird will have flown 25 miles.
09:47Yikes!
09:48That's it for today!
09:50So hey, if you pacified your curiosity, then give the video a like and share it with your
09:54friends!
09:55Or if you want more, just click on these videos and stay on the Bright Side!
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