Singapore high school maths problem stumps the Internet

A maths problem that first appeared in a test for Singapore's elite high school students has baffled Internet users around the world after it went viral, prompting a rush of attempts to solve it.

The question, involving a girl asking two boys to guess her birthday after giving them scant clues, first appeared in an April 8 test organised by the Singapore and Asian School Math Olympiads (SASMO).

It was meant for 15- and 16-year-old elite secondary school students, but swiftly went global after a local television news presenter posted it on his Facebook page Saturday.

In the question, Cheryl gives her new friends Albert and Bernard 10 possible dates when they enquired about her birthday, before separately giving each of them further clues.

Test-takers are then asked to use logic to deduce Cheryl's birthday using a short conversation between the two boys about the information given to them.

By Monday Internet users around the world were posting meticulously detailed answers to the puzzle on social media networks such as Facebook and Reddit, only to prompt a slew of comments disputing their findings and methodology.

Others posted sardonic comments about "Coy Cheryl".

"Cheryl obviously didn't want Albert and Bernard at her party. Should have taken the hint when Cheryl decided to play this little game," wrote David Leong on Facebook.

The hashtag #cherylsbirthday also trended on Twitter, while some people created funny memes about the puzzle. "If Math would grow up and solve its own problems, that'd be great," read one such meme.

The "mind-boggling" problem also made the mainstream media, with leading websites including the Guardian newspaper and Buzzfeed publishing articles about the puzzle.

- Model answer -

In a Facebook post late Monday, SASMO provided the full question and a model answer, which can be found at https://www.facebook.com/4sasmo/posts/983396811695295

The post also clarified earlier erroneous reports that the question was not posed to primary school children, saying SASMO thought it important to specify the age of the students involved so "Singapore parents will not start to worry so much".

The question was "actually from the secondary 3 and secondary 4 SASMO contests held on April 8, 2015", it said, adding it was "meant to sift out the better students".

Following relentless but mostly friendly online debate about the question's difficulty level, SASMO's executive director Henry Ong on Tuesday afternoon issued another statement.

"We are pleased that this problem has generated so much interest and thinking from the public," Ong said.

"We are not saying this problem is for every student... but if this kind of problem can be used to stretch the better students to sharpen their analytical power, why not?"

Singapore is renowned worldwide for its national maths system, which has been emulated by schools in other developed countries and cities, including New York.

Singaporean pupils are ranked second in the world in mathematics according to the latest student assessment survey by the Organisation for Economic Cooperation and Development, beaten only by their counterparts in Shanghai.

Can you do it? Are you smarter than a Singaporean ten-year-old?

Go on, give it a try.

Advice For Dog Owners (Toxocara canis)

During recent years there has been much publicity about Toxocara canis and the risks, real and imagined, associated with this parasite. Whilst the problem should not be exaggerated, it is necessary for dog owners and the public generally to know what they should do to minimise the risk.

WHAT IS IT?

Toxocara canis is a parasite that lives inside dogs’ bodies. It is a round, white worm (looks like spaghetti) and it infects, most frequently, pregnant nursing bitches and young puppies. Infection can be passed on via the mother’s milk and dog’s droppings.

LIFE CYCLE

Pregnancy activates worm larvae which may be lying dormant in the bitch. Some will migrate to the womb, others to the mammary glands and into developing puppies. Other larvae will continue their lives in the intestine of the bitch. By the time the puppy is a fortnight old, larvae already within it will have developed into adult worms. The puppy will receive even more larvae from the bitch’s milk and from being licked by her. At the same time, the bitch will be reinfected when she cleans up her puppies droppings. Toxocara eggs hatch in the puppy and the larvae burrow from the gut and migrate via the liver to the lungs where they may cause respiratory problems. Some larvae spread via the blood to other tissues where they stay dormant. Some are coughed up, swallowed and mature into adult worms in the digestive system. These lay thousands of eggs which are passed out with the droppings, to lie on grass, plants and soil, sometimes for many months, until ingested again by another dog to start the whole cycle of infection again.

HOW TO RECOGNISE WORM INFESTATION IN YOUR DOG

Whether you see worms or not, it can be assumed that all unwormed puppies and nursing bitches carry worms. Heavy infestation in puppies can cause breathing problems and even pneumonia. Puppies will also show signs of abdominal pain, may whine and adopt a characteristic straddle leg position. Infested puppies suffer retarded growth, harsh coat and have a poor, pot bellied appearance when the stomach and intestine is full of worms. In extreme cases the digestive system may become blocked. It is strongly recommended that you regularly worm your pregnant bitch and the puppies with a preparation available from your vet and follow his advice on administering times.

THE RISK TO HUMANS

The eggs of toxocara canis are invisible to the naked eye but are sticky and may be picked up from soil, grass or the animal’s coat/bedding and may be swallowed later.

Eggs which are swallowed can hatch into larvae in humans but will not develop into adult worms. However, these tiny larvae will travel around the body – usually causing no problems. Very rarely though, they can settle in particularly sensitive tissue such as the retina of the eye, where they may cause damage or even blindness. Each year about 50 cases involving eye damage are recorded. Although this number is small, the effects upon individuals are traumatic and it is prudent to take precautions. Freshly passed dog droppings are not a direct hazard because the toxocara eggs need about three weeks to mature outside the dog before they become infective. So, whilst contact with droppings is unpleasant, it does not present a risk from this point of view however, mature eggs can remain viable in the ground for some time. This is why children are more at risk (through sports fields and playing in the park - rolling on the ground) and must wash hands and faces thoroughly after playing.

WHAT TO DO
• Worm your dog properly both as a puppy and as an adult. Consult your vet for advice on the most effective wormer, as some products brought over the counter can be less effective.
• It is vital to worm the bitch as well as her puppies (seek advice from your vet)
• Do not discontinue worming because you see no worms passed. Remember dogs can become reinfected.
• When you have carried out a worming for an infestation or if you see worms in the droppings, be sure to pick up and properly dispose of it. It should be burnt or flushed down the w.c rather than buried or composted.
• Keep kennels and sleeping areas clean.
• Try and prevent your dog fouling grassed areas used by the public. If it does, clean it up immediately with a poop scoop or bag and dispose of in a “dog bin”.
• Do not allow dogs to eat off crockery used by humans.
• Do not allow dogs to lick children’s faces or share food such as ice cream and biscuits.
• Always wash your hands (and face if necessary) after handling a dog, particularly a puppy or nursing bitch.
• Ensure that children always wash their hands and face after handling a dog, puppy or nursing bitch or after they have been playing on grassed areas. Following these simple straightforward precautions will protect the health of your dog, yourself and your family as well as the general public.