MYTUTOR SUBJECT ANSWERS

397 views

How to solve the maths GCSE question about Hannah's sweets that went viral

Students took to Twitter to moan about how difficult the question was.

I agree, there is something inherently comic about the question, since you start off talking about Hannah and sweets and then - BANG - all of a sudden you get a scary-looking equation. 

But READ THE QUESTION. The question is not asking you to solve the equation. It is asking you to do some basic probability.

Let’s solve it:

If Hannah takes a sweet from the bag on her first selection, there is a 6/n chance it will be orange.

That’s because there are 6 oranges and n sweets.

If Hannah takes a sweet from the bag on her second selection, there is a 5/(n-1) chance it will be orange.

That’s because there are only 5 orange sweets left out of a total of n - 1 sweets.

The chance of getting two orange sweets in a row is the first probability MULTIPLIED BY the second one. (That’s the most important thing to learn from your lesson today, peeps!)

Which is 6/n x 5/n–1

The question tells us that the chance of Hannah getting two orange sweets is 1/3.

So: 6/n x 5/n–1 = 1/3

All we need to do now is rearrange this equation.

(6x5)/n(n-1) = 30/(n2 – n) = 1/3

Or 90/(n2 – n) = 1

So (n2 – n) = 90

Voila: n2 – n – 90 = 0

MINGWEN B. GCSE Physics tutor, GCSE Maths tutor, GCSE Chemistry tutor

1 year ago

Answered by MINGWEN, a GCSE Maths tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

511 SUBJECT SPECIALISTS

£18 /hr

Laura M.

Degree: Medicine (Other) - Bristol University

Subjects offered:Maths, Geography+ 5 more

Maths
Geography
Chemistry
Biology
.UKCAT.
-Personal Statements-
-Medical School Preparation-

“About me: I am a friendly and enthusiastic fourth year medical student studying at the University of Bristol. I found myself enjoying Maths and Sciences from an early age and eventually decided that it was my calling to be a doctor. W...”

£18 /hr

Jake A.

Degree: Engineering (Masters) - Warwick University

Subjects offered:Maths, Physics+ 2 more

Maths
Physics
Further Mathematics
Chemistry

“Who am I? Hey! I’m a personal tutor, general maths enthusiast and am presently studying Engineering at Warwick University. I currently tutor students for Maths / Physics A-level along with Maths, Physics and Chemistry GCSE. I have a g...”

£18 /hr

Laura B.

Degree: Chemistry (Bachelors) - York University

Subjects offered:Maths, Russian+ 2 more

Maths
Russian
Chemistry
-Personal Statements-

“Hello! My name is Laura and I am very passionate about science! I am currently studying Chemistry with Biological and Medicinal Chemistry at University of York and I really hope that my passion about science will inspire you!  I am ve...”

About the author

£18 /hr

MINGWEN B.

Degree: PhD in Materials (Doctorate) - Manchester University

Subjects offered:Maths, Physics+ 1 more

Maths
Physics
Chemistry

“Dr. Mingwen Bai 29 Boyton Close, London E1 4AN  sjtubmw@gmail.com   07440467703              Linkedin.com/in/drbai Personal profiles                                                           Objective: professional teaching or tutori...”

MyTutor guarantee

You may also like...

Other GCSE Maths questions

How do I solve the Hannahs sweets question from the 2015 GCSE paper?

Solve 5x + 4 = 14 + x

Solve 7x=4(x-8)

What is compound interest and how do I calculate it?

View GCSE Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok