MYTUTOR SUBJECT ANSWERS

128 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...

3 months ago

Answered by Raquel, a GCSE Maths tutor with MyTutor


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

337 SUBJECT SPECIALISTS

£18 /hr

Fraser F.

Degree: Mathematics (Masters) - Durham University

Subjects offered: Maths

Maths

“Hi, I'm Fraser! I'm a third year student at Durham University working towards a masters in mathematics. I've loved learning about maths and I hope I am able to pass that on to anyone I tutor. Sessions will be focussed around your needs...”

MyTutor guarantee

£18 /hr

Oliver T.

Degree: Mathematics (Masters) - Edinburgh University

Subjects offered: Maths, Further Mathematics

Maths
Further Mathematics

“Hello! I'm currently a 2nd year Mathematics student at the University of Edinburgh with a sturdy passion for all things Mathematics. Not only do I love Maths, I love teaching Maths and helping people with problems. In particular, I en...”

£18 /hr

Liberty A.

Degree: Mathematics (Bachelors) - Durham University

Subjects offered: Maths, Physics+ 1 more

Maths
Physics
Further Mathematics

“About Me Hi I'm Libby, I am in my first year studying Mathematics at Durham University and live in Buckinghamshire. I believe Mathematics and Pysics are fantastic subjects and I enjoy tutoring as I am able to share my passion and help...”

MyTutor guarantee

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

Solve the Simultaneous Equations -3X + 4Y=11 & X-2Y = -5 to find the values of X and Y

Rationalise 1/(√7) ?

Solve the simultaneous equation: 2x + 3y = 6, 3x + 2y = 5.

Please factorise fully: 2a^2 + 6a

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