MYTUTOR SUBJECT ANSWERS

384 views

There are "n" sweets in a bag, six are orange and the rest are yellow. If you take a random sweet from the bag and eat it. Then take at random another one and eat it. The probability of eating two orange sweets is 1/3. Show that n²-n-90=0.

We have:

n= total of sweets

6= orange sweets

(6-n)=yellow sweets (We use 6-n beacuse we know that if 6 sweets are orange, the rest must be yellow, so yellow sweets= (total of sweets-orange sweets))

If the probability of geting two orange aweets is 1/3, then:

(6/n) x (5/(n-1))= 1/3

Here, 6 over n is the probability of getting an orange sweet, we use Laplace´s Law: (number of favourable cases)/(number of total cases), that would mean: number of orange sweets/ total number of sweets. So if we have already eaten an orange sweet, there are 5 orange sweets left and the total number of sweets is n-1, that is why the second fraction is 5/(n-1)

Then we get:

30/(n^2-n)= 1/3

We try to isolate the n (as it is an equation):

n^2 - n= 30x3

n^2 - n= 90

Therefore;

n^2 - n - 90=0

Raquel L. IB Spanish tutor, GCSE Spanish tutor, A Level Spanish tutor...

10 months ago

Answered by Raquel, a GCSE Maths tutor with MyTutor


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

654 SUBJECT SPECIALISTS

£24 /hr

Scott R.

Degree: PGCE Secondary Mathematics (Other) - Leeds University

Subjects offered:Maths, Further Mathematics

Maths
Further Mathematics

“I am currently completing 2 PGCEs in Leeds. I have always had a passion for maths and my objective is to help as many as possible reach their full potential.”

£18 /hr

Diana B.

Degree: Chemistry (Masters) - Imperial College London University

Subjects offered:Maths, Chemistry+ 1 more

Maths
Chemistry
-Personal Statements-

“Imperial College London student giving Chemistry, Mathematics and Biology lessons”

MyTutor guarantee

£20 /hr

Sophia H.

Degree: Biomedical Sciences (Bachelors) - Cardiff University

Subjects offered:Maths, Russian+ 1 more

Maths
Russian
English

“Hopeful doctor in the making looking to help you reach your goals! I'm interested in everything so I am sure we will have something in common.”

About the author

£22 /hr

Raquel L.

Degree: Physics with Theoretical Physics (Masters) - Kings, London University

Subjects offered:Maths, Spanish+ 1 more

Maths
Spanish
Physics

“I am a Physics with Theoretical Physics student at King´s College London. And if there is something that I love even more than Physics and Science is learning. I love it so much that I decided to leave my country, leaving there my fam...”

You may also like...

Posts by Raquel

Do you want to make a difference in your exam? Then let me introduce you to: “los hiatos y diptongos”

Sophia (mass 47Kg) is travelling to the right with a velocity of 7.2m/s and ​Neesha (mass 68Kg) is travelling to the left with a velocity 4.8m/s. When ​they meet, they hold hands and travel off together. Give their final ​velocity and direction

There are "n" sweets in a bag, six are orange and the rest are yellow. If you take a random sweet from the bag and eat it. Then take at random another one and eat it. The probability of eating two orange sweets is 1/3. Show that n²-n-90=0.

Other GCSE Maths questions

How do you measure the gradient of a straight line joining two points?

(1) There are n children in a school. 30% of them have blue eyes. 5/12 of them have green eyes. Do more children have green or blue eyes?

How do signs change in an inequality?

GCSE: How do you find the bearing of point B from A?

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