This video is a walkthrough of probability trees and aimed at around grade 5 for GCSE maths …. please do

– stop the video

– work through the questions

– compare your solutions

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

Download a copy of the questions here: QT Probability Trees

Download a copy of the written answers here: QT Probability Trees ANSWERS

Here's the questions:

1. A coin is biased. When it is thrown, the probability that is lands on heads is 3/5. John throws the coin twice.

a) Complete the probability tree diagram.

b) Find the probability that the coins lands on heads both times.

c) Find the probability that the coin lands on heads at least once.

2. There are 6 milk chocolates and 4 plain chocolates in a box. Josh takes a random chocolate from the box and eats it. He then takes another chocolate and eats that as well.

a) Complete the probability tree diagram.

b) Find the probability that Josh eats at least one plain chocolate.

3. Carrie has two bags. In bag A there are 5 white counters and 3 blue counters. In bag B there are 3 white counters and 3 blue counters. Carrie takes at random one counter from each bag.

a) Show this information on a probability tree diagram.

b) Find the probability that both counters will be blue.

c) Find the probability that only one of the counters will be white.

4. Izaan plays cricket on Saturday and football on Sunday. The probability that he wins his cricket match is 0.4, and the probability he wins his football match is 0.55.

(a) Find the probability that Izaan wins both matches

(b) Find the probability that Izaan wins at least one of his matches.

Here's the timestamps:

0:00 Intro

0:30 First Throw Second Throw

3:05 Without Replacement

5:57 Two Bags

9:48 Two matches

These types of questions appear in all the main GCSE exam boards – Edexcel, AQA, OCR and Educas – and are fairly common for non calculator papers.

**Top Tips!**

- Always work methodically and show your working
- Why is that information in the first few lines?
- Check your calculations
- Is it a reasonable answer?

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Edexcel GCSE maths foundation November 2018 paper 2

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