# Probability basics

Instructions: answer the questions, check them carefully, and when you are sure they are all right, press submit. The number of correct answers will be displayed.

Question 1: The colours of book covers on a bookshelf have the following frequency:

Colour Frequency
white 22
green 12
yellow 14
brown 5
black 8
red 16
blue 32

What is the probability that a book chosen at random will not be blue?

Question 2: A bag contains 8 green balls, 7 red balls, and 3 yellow balls. If a ball is pulled out at random, what is the probability that the ball is green?

Question 3: A person is chosen at random from a large crowd. What is the probability their next birthday is in summer on a weekend?

Question 4: One in seven adults have a degree. How many people in a street with 87 adults would you expect to have a degree?

Question 5: A car stops for 30s at traffic lights. If a car stops once every 4 minutes at traffic lights, what is the probability that the car is stopped at lights when the driver receives a telephone message?

Question 6: A drawer contains 20 black socks and 4 brown socks, all mixed up randomly. In the dark, you have to find a matching pair. What is the minimum number of socks you need to take out to be sure to have a pair of the same colour.

Question 7: Two dice are thrown together. What is the probability of getting 8 or more?

Question 8: The pass rate for a test is 67%. How many students in a class of 27 would pass the test.

Question 9: A basket contains 5 oranges, 6 bananas, and 7 pears. A fruit is picked at random. Calculate the probability of choosing a banana.

Question 10: There are 28 students in a class. 15 study Maths and 14 study Physics. 6 students study neither of these two subjects.

How many study both Maths and Physics?

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### Quote of the day...

Les sanglots longs
Des violons
De l'automne
Blessent mon coeur
D'une langeur
Monotone

(The long sobbings of autumn violins
wound my heart with a monotonous languor)