While the lucky ones are enjoying life during this busy September term break, Miss Loi gets to ‘enjoy’ the cool night breeze in Novena as she leaves The Temple later & later each day, causing her to miss more & more episodes of the 11pm re-run of a Channel 8 drama involving a villainous cop.
As fate would have it, while she was walking to her car and well on her way to missing tonight’s crucial episode of the Channel 8 drama (where it’s revealed if the villainous cop managed to kill the lead actress), she crucially missed hearing the hurried footsteps of a villainous robber in hot pursuit by the police behind her.
And in an instant, a shell-shocked Miss Loi found herself locked in an utterly unromantic embrace with the burly robber, with his gun pointing at her head.
你们别过来啊！不然我一枪崩了她！(Stay away from me! Or I’ll blow her stupid aunty hairstyle into oblivion!)
… screamed the man in his Mainland Chinese accent.
Unbeknown to the robber, however, a police officer was communicating with her via her geeky bluetooth earpiece hidden behind that humongous aunty hairstyle, for he recognized Miss Loi and had resourcefully found her number earlier from a website known as https://www.exampaper.com.sg/blog.
Don’t worry my Sexy Maths Tutor, our sharpshooters are standing by to take out your captor.
But unfortunately, our 100% bullseye-guaranteed 神枪手 Chief Marksman is still on holiday in Beijing after representing Singapore at the Olympics. And we’re now left with two backup sharpshooters …
The following table shows the results from the last shooting practice of the two sharpshooters:
| Distance from center of target (mm) | ||||||
|---|---|---|---|---|---|---|
| Sergeant Bobo | 47 | 9 | 1 | 4 | 60 | 100 |
| Corporal Pa Jiao | 32 | 35 | 47 | 39 | 40 | 45 |
For each of them, calculate
- the mean distance from the center of the target,
- the standard deviation.
- Who should Miss Loi choose to be her sharpshooter? Explain briefly why.
As I’ve failed EMaths in my O-Levels, please let me know which sharpshooter would you prefer to save you from the robber!
Miss Loi is beginning to hurt from the gun barrel pressing on her forehead …
With the introduction of Standard Deviation to the New EMaths Syllabus this year, it’s almost certain that you’ll get to see a part of your question on Data Analysis that requires you to calculate the mean and standard deviation of two (or more) sets of data and THEN use these values to compare the sets of data with a brief explanation.
For this, besides recalling the right formula to use for the Standard Deviation S i.e.
(for ungrouped data i.e. those without frequencies)
or 
(for grouped data i.e. those with frequencies)
it’s important to understand that while the Mean represents the average value of a data set, the Standard Deviation represents the spread and consistency of the data set. In layman terms, you can consider standard deviation as the average deviation of the data set from its mean.
And once you’re convinced that standard deviation questions are pretty straightforward and not as scary as they sound, you can put yourself in a more advantageous position by familiarizing yourself with the SD or STAT of your scientific calculator to cut down your calculation time and lower the risk of careless mistakes.
As all calculators are born unequal with different buttons, please refer to your calculator’s manual and practise how to use buttons like , , etc. to solve the above question and save Miss Loi in record time!
P.S. When using the SD/STAT Mode in your calculator, do make a habit of:
- Clearing your data each time before entering a new set of data!
- Verifying that you’ve not missed out any data in the set by checking the total number entered i.e. via the button!
P.P..S. Actual buttons may differ on your calculator model.
