Page 274 - ICSE Math 8

MENTAL MATHS

1. Choose the correct option.
(a) The collection of all possible outcomes of a random experiment is/are called:
(i) trials (ii) events (iii) sample space (iv) probability
(b) If a coin is tossed 3 times, the number of possible outcomes are:
(i) 8 (ii) 6 (iii) 10 (iv) 4
(c) Two fair dice are rolled simultaneously. The probability of getting the sum as 5 is:
1 2 1 4
(i) (ii) (iii) (iv)
6 3 9 9
(d) In a pack of 52 cards, the number of face cards are:
(i) 3 (ii) 6 (iii) 9 (iv) 12
(e) If A denotes the happening of an event, then P( A ) is:
(i) 1 – P(A) (ii) P(A) – 1 (iii) 1 + P(A) (iv) P(A)
2. Write True or False.
(a) When a coin is tossed once, there are 4 outcomes.
(b) The probability of an event lies between 0 and 1 (0 and 1 both inclusive).
(c) An outcome of a random experiment is also an event.
2
(d) The probability of getting an even number in one throw of a die is .
(e) There are 4 suits in a pack of 52 cards. 5
3. Fill in the blanks.
(a) Performing a random experiment is called a _____________.

(b) For any event A, P(A) + P( A ) = _____________.
(c) The number of outcomes in two throws of a die are _____________.
(d) The probability of drawing a black card from a pack of 52 cards is _____________.
(e) An event obtained by combining two or more sample points is called _____________.

PRACTICE TIME

1. Two fair dice are rolled simultaneously 67 times. A doublet is obtained 8 times. Now, if the pair of dice
are rolled simultaneously again at random, what is the probability of getting a doublet and probability of
not getting a doublet?
2. A box has coupons numbered from 1 to 100. A coupon is picked. Find the probability that the number
on the coupon is:
(a) even (b) a multiple of 3 (c) a prime number (d) a factor of 100
3. A bag contains 6 red marbles, 9 white marbles, 5 green marbles. What is the probability that if one marble
is taken out of the bag at random, it will be:
(a) red (b) white (c) not green
4. If there is a spinning wheel with 3-blue sectors, 1-red sector and 1-green sector of same size, what is the
probability of getting a blue sector?
5. A card is drawn from a well-shuffled deck of 52 cards. Find the probability of getting:
(a) a black card (b) a red card (c) a diamond card (d) a black number card
(e) a face card (f) an ace of hearts (g) a picture card
6. In the game of cricket, there are in all 15 people present on the field at a time. What is the probability
that after being hit by the batsman, the ball will hit the empire?

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