Comparison: You bigger or I bigger? >.<

First things first, a belated Happy 1st (month) anniversary to Eatyourmaths on the 5th of August! Thank you to the hordes of visitors who brave the evening jam or lunchtime jam to come Eatyourmaths with Mr Fong! I'm truly grateful. :) It has been 30 posts, from the hugely-popular debuts like this and this, to adverts, lame videos, to tips for everyone engulfed by exams, this blog has seen a massive lengthening of it's sidebar, getting fatter and fatter.. Must be the old age, LOL.



This post is here as dear William, a fellow patron of Eatyourmaths, took time off from his busy blogging schedule (Go check out his blog!) to send me a request for a question! Thank you! Mr Fong welcomes any Maths question from Primary school to Secondary School, and here starts the torture:



"There is a fish tank. You can drain the water with a pipe in 9 minutes. If you add water from another pipe you can fill it up in 6 minutes. If you drain and fill the fish tank at the same time, how long do you need to fill it up?"



Note: Mr Fong understands this is his holiday, and it is also a National Day Holiday for his dear students, but he has decided to get back to mild work to signify the "hard work put in by our ancestors". Yay (I am not an ancestor ok) !



Anyway this is a Comparison question, and you can kindly ignore the second part of my title, heh. According to Mr Fong, what this question is asking you is "how long do you need to fill it up", so please do not answer with classics like, "All the fish die." (oh NOOOOOO!!!)



Hear, hear...Mr Fong can already hear the noises of dissent from the crowds, like "WHY ARE WE LEARNING ABOUT FISH TANKS IN EATYOURMATHS TUTORIALS?!!! :(((((((" and "I WANT MY HOLIDAY!!!", so he has made the magnanimous decision of doing it himself! Hope that this will appease the hordes of protestors now trying to lynch the doors of my dear classroom, ehhhh!



OK,now let me suffer...



This is a question very similar to the inverse function question you savoured once (still remember anot?!), and using the similar method:



1. All the water is drained in 9 minutes. In 1 minute: 1/9 of the tank is drained.

2. All the water can fill the tank in 6 minutes. In 1 minute: 1/6 of the tank is filled.

3. Putting both pipes in at the same time, in 1 minute: Water in the tank = Amount filled - Amount drained. = 1/6 - 1/9 = 3/18 - 2/18 = 1/18 of the tank is filled.

4. 1/18 of tank filled: 1 minute.

18/18 of tank filled: 18 minutes.



Hope this is helpful.



Anyway, Mr Fong would want to congratulate Sidney, a faithful patron of Eatyourmaths tutorials, for topping her class in Mathematics Paper 1! This is after she finished last in class for the previous exam, and now, through sheer hard work and determination and Mr Fong's tutelage, she has managed to make this amazing turnaround. She is the perfect example of how hard work can get you through any problem, let alone examinations!



Congratulations, and Mr Fong says good bye! :D I would like to 'tank' you for reading these posts,LoL.