The answer
(a) 37 g
(b) 209 g
O-Level E-Math 2017 Paper 1 Question 3 · Verified worked solution by the Genius Plus Academy teaching team
What this question tests
This is Question 3 of the O-Level E-Math 2017 Paper 1. It tests range from a stem-and-leaf, in the Averages & spread (raw data) area. It is worth 2 marks: 1 + 1. It is a worded / diagram-based question, so open your Ten-Year Series (TYS) or the official paper at this question, then follow our full worked solution below.
There are \(4 + 6 + 7 + 3 = 20\) values. The smallest is \(191\) g and the largest is \(228\) g.
(a) Range \(= 228 - 191 = 37\) g.
(b) With 20 values, the median is the mean of the 10th and 11th values. Counting up: the first row ends at the 4th value, the second row at the 10th value (\(= 208\)), and the 11th value is the first of the third row (\(= 210\)). Median \(= \dfrac{208 + 210}{2} = 209\) g.
Answer: (a) 37 g
(b) 209 g
Same structure, different numbers
Swap the constants, dress a quadratic as a length, hide a derivative inside an integral, and a student sees a brand new problem. The structure underneath is the same, and so is the method. Once a student can name the structure, a whole row of questions that look different start to open the same way.
That is where marks really leak: in choosing the method, not in the algebra that follows. We call it Lock and Key, name the lock, then the key follows.
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Genius Plus Academy · O-Level & IP Mathematics
Our O-Level E-Math tuition trains the same recognise-the-structure method these worked solutions show, taught by a team that has marked these papers for years. It runs within our weekly Secondary Math programme, Sec 1 to 4 and IP.
It is a range from a stem-and-leaf question from Averages & spread (raw data), worth 2 marks: 1 + 1.
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