*Fighting!* ]]>

A little scary that the values in this question seem a tad too 'realistic' eh?

]]>That's right. The median is the *value* of the middle term of the set of data arranged in increasing order. In this case, the middle term is the 60th out of the 120 students, and it's corresponding marks for Paper 2 is 60.

[2] 72-45

= 27

Yes if you refer to the little diagram Miss Loi has drawn up. The interquartile rage is `Q`_{3}-`Q`_{1}

`Q`_{3}

= Marks at 75% of 120

= Marks at 90

≅ 72

`Q`_{1}

= Marks at 25% of 120

= Marks at 30

≈ 45

So `Q`_{3}-`Q`_{1} ≈ 72-45 ≈ 27

Again Miss Loi would like to stress that we're looking for the *values* i.e. those on the horizontal axis corresponding to the data on the vertical axis. Many students make the careless of mistake of reading directly off the vertical axis.

[3] 120-85

= 35

Righto! The keyword here is *more than 70 marks*, which includes all who scored between 70-100. From the Paper 2 graph you get the lower limit of 85 students (who scored 70) and the upper limit of 120 students (who scored 100). So the number of students in this range is 120-85 = 35 students.

[4] From the graph,

pass mark would be 65.

You got pwned here! A good way to check is if you set 65 as the passing mark, and if you look at the graph again, 0-72 students scored between 0-65 marks. Will you PASS your exam if you score zero? No way! So you actually FAILED 60% of the students with your cutoff of 65!

Will you PASS if you score 100? Of course. So you should instead look at the *top 60%* of the frequency axis in the graph, i.e. 60% of 120 *starting from 120* (instead of starting from 0). Therefore you should be getting the passing mark from 40% of 120 = 48 ⇒ passing mark is around 55.

BE VERY CAREFUL IN THESE KIND OF QUESTIONS! Many students got caught out here!

[5] From the graph,

mark= 83 {approx}

Let's check again ... if you set 83 as your distinction mark, you'll get 114 (95%) students scoring 0-83, which means they failed to attain the distinction grade, which means only 5% get it. This time you correctly used the *top 5%* so you're right!

Actually part 5 requires the same method to solve as part 4, and your 'instincts' served you well when it's the top 5%. But things don't look so obvious when it's the top 60% 😉

Paper 1 is more difficult, as median mark of Paper 1 is lower than the median mark of Paper 2.

Absolutely! Those who're still not sure let's chant the mantra together!

Higher median = easier paper.

Lower median = more difficult paper.

Repeat this 20x before you go to bed and always remember that for medians and quartiles we're interested in the *corresponding values* on the horizontal axis. Don't make this careless mistake in your exam!

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]]>As mentioned earlier, no point worrying about things beyond your control okay?

Rumours are now flying all over the place as to what's the A1 cut-off.

But the perennial question remains: who assigns your grades? Is it Cambridge or SEAB aka the War Council? If it's Cambridge then the pool of people is more spread out but if it's SEAB then you're probably competing with a pool of people at the higher-end, namely Singaporeans and our foreign 'talents'.

Miss Loi has heard from somewhere that gradings were being determined through some 'collaborative meetings' between Cambridge and SEAB reps. And if that's true, then it's highly probable we're looking at the latter case due to SEAB's involvement.

In any case, Miss Loi isn't 100% sure on this and is still waiting for anyone in the know to confirm this.

But then again it's always good to aim high 🙂

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