Probability Equations - Quick Reminder - GCSE Maths Grade 8

#3minutemaths #SimonDeaconmaths
This video is a quick reminder of probability equations for GCSE maths, and is aimed at around grade 8.

- stop the video
- work through the questions
- compare your solutions

I hope the video helps and please do leave a comment - thanks!

Here's the questions (first one on the video):
1. There are some green counters and white counters in a bag.
The ratio of green counters to white counters is 4:1.
Two counters are removed at random.
The probability that both the counters are white is 1/30
How many counters were in the bag before any counters were removed?
2. There are 5 green counters and x white counters in a bag.
Two counters are removed at random.
The probability that one counter is green, and the other counter is white is 6/11
How many white counters were in the bag before any were removed?
3. There are x pens in a box.
8 of the pens are blue, and the rest are red.
Ahmed takes a random pen from the box and does not replace it.
He then takes another random pen from the box.
The probability that Ahmed takes two red pens is 15
(a) Show that x^2 - 21x + 90 = 0
(b) Find the value of x

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Visit playlists to help you get more from your studies

GCSE - everything you need to know to get great grades

How to solve linear equations

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[tahakarim]

Oh my is this not grade 9??
Sir I would think this is grade 9 level but only grade 8?

[nusratfaras]

Hi, my son is in year 11, he has started solving past papers, but he able to solve only 50% questions he skips most of the questions when I asked him he tells that it's very hard & not taught in the school. I m worried about his exams😔

[loadeddiaper]

Hi i am going to year 11 in a new british school...Can you tell me some math videos so i can train myself before the semester starts