CAMBRIDGE CHECKPOINT MATHEMATICS CLASS 8 EX 15.3 ANSWERS_2013 EDITION

 EX 15.3 SOLUTIONS

 

 I Xavier throws two fair dice together. What is the probability of scoring:
   a two fours
b no fours  
c exactly one four?
 2 Mia throws two fair dice and adds the scores.
   a What is the smallest possible total?
   b What is the largest possible total?       
   c What is wrong with Mia's argument          

3 Shen throws two dice and adds the numbers together.
   a What is the most likely possible total?        
b What is the least likely possible total?
   Find the probability that the total will be:
   c 2 d 7 e less than 7 f an odd number                             g a prime number.

4 Razi throws two dice. Find the probability that:
   a the numbers are the same       b the difference between the two numbers is 2.

5 Dakarai spins a coin and throws a dice. One possible outcome is a head and a 6.
   a Show that there are 12 mutually exclusive outcomes and list them in a table.
   b Find the probability of scoring:
     i a tail and a 1      ii a head and an even number        iii a tail and a or a 6.

6 Alicia has two three-sided spinners.
   One shows the numbers 1, 1, 3.
   The other shows the numbers 2, 3, 5.                                   2   3    5
   a Copy and complete the table to show
     the total score of the two spinners.                                     4
   b Find the probability of a total of:
     i 3       ii 6       iii 5 or more     iv an even number.

7 Oditi throws two dice and multiplies the scores together.
   a Draw a table to show the possible values of the product.          The product is the result of
   b How many different products are possible?                         multiplying two numbers.
   c Find the probability that the product is
     i 12      ii not 12      iii less than 12    iv more than 17       v an even number.

8 Hassan has four blue pens and a red pen in his pocket.
   He takes out one without looking, and then he                    Second pen
   takes another.                                                a Copy and complete the table to show the possible
     selections.                                    
   b Why are there Xs down the diagonal?
   c Find the probability that:
     i both pens are blue ii the first pen is red         
     iii one of the pens is red.

9 Shen and Tanesha play crock, paper, scissors. They simultaneously make a sign for one of the items.
   a Make a table to show the different possible outcomes.
   b If each person chooses at random, what is the probability that they will not choose the same
     thing?
   c Rock beats scissors. Scissors beat paper. Paper beats rock. What is the probability Shen beats
     Tanesha, if they play one game?