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The Foolish Things People Do For A Sexy Maths Tutor

Tuition given in the topic of E-Maths Tuition Questions from the desk of Miss Loi at 3:28 pm (Singapore time)

Updated on

(If you have no idea what this is all about, please read Part 1 first)

Upgraded HDB Estate

The Ah Beng’s sprawling
(& fully-upgraded) territory

He surveyed his vast territory from the common corridor of his HDB flat, watching families going about their Chinese New Year visits, and young couples strolling along with their Valentine’s Day bouquets in hand.

The years had been good to him, as the Ah Beng rose and rose through the ranks of his secret society to become the dreaded right-hand man of his Triad Chief, having applied the mathematical skills he had picked up to impress with his lightning speed of calculating exorbitant compound interests for the entire loan shark network, and his ability to deduce (using mensuration formulae) with frightening accuracy the exact volume of paint needed to be splashed on each victim’s door to avoid accidental damage to neighbouring property.

But despite his stellar career in a finance industry that would’ve made some L1R5 ≤ 6 pts students green with envy, there remained a sense of emptiness that gnawed at his heart …


A pesky voice jolted him from his reverie.

You are still single?????! When are you going to find a husband?!

Sufficiently intrigued, he walked to the HDB unit where the commotion came from, and peered through the window panes, just like the old days.

Better quickly find a boyfriend while you are still pretty! Your cousin Ling Ling’s already pregnant with her second child!

In a typical Hong Kong drama scene when the 插曲 (i.e. secondary track) usually starts playing, the Ah Beng‘s heart skipped a beat when he found himself staring at a woman seated in the room – the sole reason for his feeling of emptiness all these years. And though she was beginning to look a bit rough on the edges, she was still as stunning to him as when he first set eyes on her many years ago (thanks to the facial products she has been using).

So when are you planning to get married? Don’t you think you’re too old for ang bao???

As she started to look helplessly distressed in the face of her relatives’ relentless interrogation, he sensed that it was now or never. And so in a classic 不管三七二十一 (don’t-care-3-7-21) moment, he barged into the room to yell in perfect Hokkien


After a prolonged period of awkward silence, one of the aunties recovered from the shock and muttered

Aiyoh got boyfriend already don’t be shy to tell us lah! By the way, what’s your name and occupation Handsome?

Recognizing that “Triad Chief’s right-hand man” won’t be an appropriate answer on this occasion, the Ah Beng smiled and confidently replied with the first occuption that crossed his mind

Everyone calls me ‘Smiling 哥’. I am a Maths Tutor.

Oooh you’re a Maths tutor too just like my Loi Loi? Such a match made in Heaven!

By the way if you don’t mind, I have a maths question that has been troubling me all night. Should be chicken feed to a maths expert like you!

At the Chinatown market last night, a stall keeper sold me two jars of pineapple tarts at the same price. He claimed that, while he made a profit of 20% on one of them, he also made a loss of 20% on the other – hence he “didn’t make any money from me”.

In order to find out once and for all if he was telling the truth, can you help me calculate the overall percentage gain/loss on selling the two jars of pineapple tarts?

Given that the Ah Beng‘s maths has become rusty ever since he delegated most of his calculation tasks to his runners after he became the right-hand man (see, maths is all about constant practice!), can you please do a good deed on this Chinese New Year/Valentine’s Day to help him get out of this fix???

P.S. ‘Smiling 哥’ actually turned desperately to look at the real maths tutor for help, but all he got was a fierce glance from an angry Loi Loi, since afterall, she had no idea who he was.


Revision Exercise

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Comments & Reactions


  1. mathslover's Avatar
    mathslover commented in tuition class


    The fierce glance from the angry maths tutor sent Smiling 哥 dreaming and drooling. All those memories of years gone by when he had eavesdropped on neighbours' and strangers' maths tuition while conveniently stalking his 梦中情人 replayed in his head like some black-and-white movie.

    ... ...

    Sleeping memories of past mathematical endeavours awoken in his head.

    He took out his pen and notepad and starting writing away, talking as he wrote, trying to emulate his 梦中情人.

    "Let the selling price of each jar of pineapple tarts be $x.

    Since he made a profit of 20% on Jar 1, $x is therefore 120% of the cost price of Jar 1. You know why? Because the cost price is 100%, and the profit is 20%, so the selling price is 100% + 20% = 120%, understand?

    Cost price of Jar 1 = ${x/{120%}} * 100% = $({5x}/6).

    Since he made a loss of 20% on Jar 2, $x is therefore 80% of the cost price of Jar 2. You know why? Because the cost price is 100%, and the loss is 20%, so the selling price is 100% - 20% = 80%, understand?

    Cost price of Jar 2 = ${x / {80%}} * 100% = $({5x}/4).

    Adding up the cost price of both jars we get $({5x}/6) + $({5x}/4) = $({25x}/12)
    Adding up the selling price of both jars we get $2x.

    Since $({25x}/12) > $2x he made a net profit of $(x/12).

    Miss Loi: *points to the statement above with trembling fingers* 你活得不耐烦了是吗?


    Now to find the percentage profit, you just have to use [profit / cost] times 100%. Like this,

    {{${x/12}}/{$2x}} * 100% = (100/24)% = 4.17% (3s.f.).

    Get it?

    You have been cheated lah! Next year when you go CNY shopping, remember to call me along hor!"

    He laughed a confidently evil laugh as he handed the scribbled workings to the auntie, then sat down and admired his 梦中情人 at close range...

  2. clarion-x's Avatar
    clarion-x commented in tuition class

  3. mathslover's Avatar
    mathslover commented in tuition class


    Before the auntie could scrutinise the working further, and upon hearing what he thought was a faint snicker from his 梦中情人, he quickly snatched the working paper back.

    "No! No! No! Wait!"

    "Since $({25x}/12) > $2x he made a net LOSS of $(x/12).

    So, using [loss / cost] x 100%, like this...

    {{$(x/12)}/{$({25x}/12)}} * 100% = 4%

    He made a 4% loss. Muahahahahha!!!

    Now confirm correct already!"

    With that, he pushed the paper back across the table, conveniently helped himself to a mandarin orange out of the basket on the table, and settled back down again, grinning confidently and 光明正大地盯着他心里的她。。。

  4. Miss Loi's Avatar
    Miss Loi Friend Miss Loi on Facebook @MissLoi commented in tuition class


    Like the scene off The Good, The Bad & The Sexy Ugly, the Ah Beng, the Sexy Maths Tutor, and the Aunty faced each other in a Mexican-style standoff.

    The Chinese New Year banter had long ceased. The silence was deafening. The tense minutes seemed like hours as the seconds ticked away.

    The Maths Tutor's peer was intense, as she sized up the Ah Beng while he tossed the mandarin orange up and down with trembling fingers that betrayed his confident smile.

    Just moments ago, beads of sweat were forming on his forehead as he approached with trepidation this Sec One percentages question which had caught out many of her students - mainly due to the absence of any given cost/selling price.

    She wondered who this man was as, despite a near careless mistake that could be attributed to exam stress, he was somehow able to know that

    • Recognize that 100% always refers to the cost (original) price in profit and loss statements.

      ⇒ Overall % profit/loss = [(total selling price − total cost price)/total cost price] × 100% ----- (1)

    • Let the selling price be x since it's the common (and most convenient) unknown for both jars.

      Hence total selling price = $2x.

    • Remembering once again that 100% refers to the cost:
      1. 20% profit for Jar 1
        ⇒ 120% of cost of Jar 1 = $x
        ⇒ Cost of Jar 1 = ${x/{120/100}}=${5x}/6

      2. 20% loss for Jar 2
        ⇒ 80% of cost of Jar 2 = $x
        ⇒ Cost of Jar 2 = ${x/{80/100}}=${5x}/4

      ∴ total cost price = ${5x}/6 + ${5x}/4 = ${25/12}x

    • Sub the total selling price and total cost price in (1) to obtain the overall % as

      {({2x - {25/12}x})/({25/12}x)} * 100% = -4% (−ve sign ⇒ LOSS)

    The standoff was finally broken by the Aunty ...

    AIYOO! Smiling 哥 you are sooo smart! No wonder you and my Loi Loi are together!

    I always knew that the pineapple tart seller has a secret crush on me!

    ... that was the cue for the maths tutor to bid everyone goodbye and leave the room abruptly.

    *cue for 插曲 to play again*

  5. clarion-x's Avatar
    clarion-x commented in tuition class


    Smiling 哥 dashed out of the house at once, only to be greeted by the "clack clack" of Loi Loi's 5-inch killer heels,as it struck on the concrete flooring of the corridor. As Loi Loi's figure receded gradually into the distance, it created an unfillable vortex in Smiling 哥's heart; he stretched out his arm, hoping futilely that the fair damsel would turn around and embrace him and his feeling for her.
    Every "clack" that her heels made with the floor seemed to plunge into his heart like a sharp dagger. His heart bled. Profusely. But who would care about him? 🙁

  6. clarion-x's Avatar
    clarion-x commented in tuition class


    *Post note*
    Eh I type this continuation until I also a bit emo. Haha.

  7. Miss Loi's Avatar
    Miss Loi Friend Miss Loi on Facebook @MissLoi commented in tuition class



    追女仔 (chase girls) FAIL!

    *clack clack clack clack clack ... *

  8. mathslover's Avatar
    mathslover commented in tuition class


    Smiling 哥 (towards Loi Loi's 消失的背影): 我都等了19年,我会等下去的!

    Smiling 哥 (towards his sprawling territory viewed from the corridor, arms outstretched):我一定要追到你!

    [Freeze screen]

    *credits start running*

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