MYTUTOR SUBJECT ANSWERS

55 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...

2 months ago

Answered by Raquel, a GCSE Maths tutor with MyTutor

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

328 SUBJECT SPECIALISTS

£18 /hr

Emma D.

Degree: Philosophy and Psychology (Bachelors) - Durham University

Subjects offered: Maths, Philosophy and Ethics+ 2 more

Maths
Philosophy and Ethics
Biology
-Personal Statements-

“First year Durham University student with exepertise in Maths, Biology and Religious Studies.  Friendly, dedicated and personable student who has prior experience working as a tutor and advisor. ”

MyTutor guarantee

£20 /hr

Amruni C.

Degree: Medicine (Bachelors) - Imperial College London University

Subjects offered: Maths, Science+ 1 more

Maths
Science
-Medical School Preparation-

“Hi, I’m Amruni and I’m a medical student at Imperial College London. For the past 2 years I have been tutoring Maths and Science to students from 11+ to GCSE and have absolutely loved being able to share my passion for science and mat...”

£18 /hr

Simone V.

Degree: Biochemistry (Bachelors) - University College London University

Subjects offered: Maths, Science+ 4 more

Maths
Science
French
Dutch
Chemistry
Biology

“I believe that the most important thing a tutor can do is to motivate the student and make learning fun! That’s exactly what I want to achieve during a session. At the end of a session, I want you to feel like you learned something in...”

About the author

£18 /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 work out the area of a triangle?

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

How do I solve equations with unknowns in the denominators?

How do you factorise a quadratic equation?

View GCSE Maths tutors

Cookies:

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

mtw:mercury1:status:ok