Question

An 8-sided fair die is rolled twice and the product of the two numbers obtained when the die is rolled two times is calculated. Draw the possibility diagram of the product of the two numbers appearing on the die in each throw Use the possibility diagram to calculate the probability that the product of the two numbers is A prime number Not a perfect square A multiple of 5 Less than or equal to 21 Divisible by 4 or 6

Answer 1

Answer:

(a)See below

(b)I) 0.125  (ii)0.828125   (iii)0.234375   (iv) 0.625   (v)0.65625

Step-by-step explanation:

When an  8-sided die is rolled twice, the sample space is the set of all possible pairs (a,b) where a is the 1st outcome and b is the 2nd outcome.

The sample space is:

$[(1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6),(1, 7),(1, 8)\\(2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6),(2, 7),(2, 8)\\(3, 1), (3, 2), (3, 3), (3, 4), (3, 5), (3, 6),(3, 7),(3, 8)\\(4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6),(4, 7),(4, 8)\\(5, 1), (5, 2), (5, 3), (5, 4), (5, 5),(5, 6),(5, 7),(5, 8)\\(6, 1), (6, 2), (6, 3), (6, 4)(6, 5),(6, 6),(6, 7),(6, 8)\\(7, 1), (7, 2), (7, 3), (7, 4)(7, 5),(7, 6),(7, 7),(7, 8)\\(8, 1), (8, 2), (8, 3), (8, 4)(8, 5),(8, 6),(8, 7),(8, 8)]$

PART A

The sample space of the product a*b of each pair forms the required possibility diagram.

This is given as:  

$1, 2, 3, 4, 5, 6,7,8\\2, 4, 6, 8, 10, 12,14,16\\3,6,9,12,15,18,21,24\\4,8,12,16,20,24,28,32\\5,10,15,20,25,30,35,40\\6,12,18,24,30,36,42,48\\7,14,21,28,35,42,49,56\\8,16,24,32,40,48,56,64$

PART B

I) A prime number

The number of products that gives prime numbers = 8  

The probability that the product is a prime number

$=\dfrac{8}{64}= \dfrac{1}{8}\\=0.125$

ii) Not a perfect square  

Number of products that results in perfect squares =11

The probability that the product is not a perfect square

$=\dfrac{64-11}{64}= \dfrac{53}{64}\\=0.828125$

iii) A multiple of 5  

Number of products that are multiples of 5=15

 The probability that the product is a multiple of 5

$=\dfrac{15}{64}\\=0.234375$

iv) Less than or equal to 21

Number of products which are less than or equal to 21=40

 The probability that the product less than or equal to 21

$=\dfrac{40}{64}=\dfrac{5}{8}\\=0.625$

v) Divisible by 4 or 6

Number of products divisible by 4 or 6= 42

 The probability that the product is divisible by 4 or 6

$=\dfrac{42}{64}=\dfrac{21}{32}\\=0.65625$