Sherlock Holmes GCSE Maths Challenge – episode 4 solution

Many congratulations to the Episode 4 winners of our Sherlock Holmes maths competition:

Jonathon Cox at The Littlehampton Academy

for successfully working out where Holmes and Watson must go next.

And the answer is:


We’ll be sending the winners a FREE Class set of Longman’s unique AQA A-A* and G-F Practice Books (15 copies of each) and a tin of Cadbury’s Heroes.

Coming up next… a spot of Christmas shopping in Episode 5 on Wednesday.

Here is the winning solution to episode 4:

The solution to how far away Moriarty is from the tunnel.

The path of the firework is y=300+44x-x^2. This is a quadratic so using the quadratic formula to find x when y=0

x= (-b +/- square root (b^2 – 4ac))/(2a)

where a=-1, b=44 and c=300

x = (-44 +/- square root (44^2 – 4X-1X300))/(2X-1)

x = (-44 +/- square root (1936 + 1200))/(-2)

x = (-44 +/- square root (3136))/(-2)

x = (-44 +/- 56)/(-2)

Either x = (-44 – 56)/(-2) = -100/-2 = +50 (where the tunnel is)

or x = (-44 + 56)/(-2) = 12/-2 = -6 (where Moriarty must have fired the firework from)

 So 50 – -6 = 56 metres away from the tunnel

 Moriarty is 56 metres away

 The Code.

 Using the Coordinates of the Tate Modern (34, 14) and the code FG DG.

Using a shifted substitution D=1, E=2, F=3 etc

The Coordinates generated from substitution of CK EE gives (08, 22) which give the coordinates for Oxford Circus

 Moriarty’s Target is Oxford Circus

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