CAMBRIDGE CHECKPOINT MATHEMATICS CLASS 8 EX 15.2 ANSWERS_2013 EDITION

 EX 15.2 SOLUTIONS

 

1 Ahmad throws a dice. Find the probability that it is:         a a 2               
b not a             
c not a    5              
d not a multiple of 3.

2 Maha writes the letters of the word 'MATHEMATICS' on separate cards.
    She takes one card at random. Find the probability that the letter on the card is: a an M              
b not an M          
c S or T            
d B                             e before J in the alphabet.

3 In the game of 'Scrabble' there are 100 tiles. Each has one letter or a blank.

    The table shows the numbers of tiles with vowels.

    One tile is taken at random. Find the probability that it is:              
a A                 
b U  
c not O
d a vowel
e not a vowel.

4 Harsha chooses a number at random from this grid. Find the probability that the number she chooses is:                                                            a 27

b in the bottom row                                 c in the first column
d not in the last two columns.
                                                    Harsha chooses another number at random from the                                     Find the probability that her number is:                                   e less than 10
f more than 10                  g not 10
h more than 20.

5 This is a calendar for April in one year.
Anders chooses a day at random. Find the probability that the day he chooses is:
                                                    a a Monday                 b not a Monday                  c 16 April
d not 16 April
e a Thursday or a Friday.

6 Zalika chooses one day of the year 2015 at random.
a What is the probability that it is: i 5 August ii not 5 August iii in August iv not in August?
b Suppose she chose a day in 2016 instead of 2015. Which probabilities in part a would be greater
     now?

7 A computer generates a single-digit random number. It could be any number from 0 to 9.
   Find the probability that it is:
   a 0           b not 0   c a multiple of 3    d 3.5      e less than 7.

8 A computer generates a two-digit number random number. It can be any number from 00 to 99.
   Find the probability that it:
   a is 99       b is not 99     c has no 9s in it    d has at least one 9 in it.

9 When Razi throws two coins there are four equally likely outcomes.
                                                                         H = head
                                                                         T = tail
   a How many of these four outcomes will give:
     i two heads     ii one head and one tail iii two tails?
   b If two coins are thrown, what is the probability of getting:
     i two heads     ii one head and one tail iii two tails?

10 Sasha tosses three coins together.
   a Explain why there are eight equally likely outcomes.
   b Find the probability that there will be:
     i three heads   ii three tails iii two heads and one tail iv two tails and one head.