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Total number of pens = 144
Total number of defective pens = 20
Number of good pens = 144-20 = 124
She will buy if the pen is good.
Therefore, the probability that she buys = probability that the pen is good =

Here, Total outcome is the area of the rectangle and favourable outcome is area of the circle.
Area of the rectangle =
Area of the circle =

The six faces of the die contains : {A,B,C,D,E,A}
Total number of letters = 6
(i) Since there is only one D,
number of favourable outcomes = 1
Therefore, the probability of getting D is

The six faces of the die contains : {A,B,C,D,E,A}
Total number of letters = 6
(i) Since there are two A's,
number of favourable outcomes = 2
Therefore, the probability of getting A is

Total number of discs = 90
Numbers between 1 and 90 that are divisible by 5 are {5,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80,85,90}
Therefore, total number of discs having numbers that are divisible by 5 = 18.

Total number of discs = 90
Perfect square numbers between 1 and 90 are {1, 4, 9, 16, 25, 36, 49, 64, 81}
Therefore, total number of discs having perfect squares = 9.

Total number of discs = 90
Number of discs having a two-digit number between 1 and 90 = 81

Total number of bulbs = 20
Hence, total possible outcomes = 20
Number of defective bulbs = 4
Hence, the number of favourable outcomes = 4

Total number of bulbs = 20
Hence, total possible outcomes = 20
Number of defective bulbs = 4
Hence,number of favourable outcomes = 4

Total number of pens = 132(good) + 12(defective)
Hence, total possible outcomes = 144
Number of good pens = number of favourable outcomes = 132

When the queen is kept aside, there are only 4 cards left
Hence, the total possible outcomes = 4
(2b) Since there is no queen left.
Hence, favourable outcome = 0
Therefore, the probability of getting a queen is 0. Thus, it is an impossible event.

When the queen is kept aside, there are only 4 cards left
Hence, the total possible outcomes = 4
(2a) There is only one ace.
Hence, favourable outcome = 1
Therefore, the probability of getting an ace is 0.25

Total number of cards = 5
Hence, the total possible outcomes = 5
(1) There is only one queen.
Hence, favourable outcome = 1

Total number of cards in a well-shuffled deck = 52
Hence, total possible outcomes = 52
(6) Let E be the event of getting the queen of diamonds
Hence, the number of favourable outcomes = 1
Therefore, the probability of getting the queen of diamonds is

Total number of cards in a well-shuffled deck = 52
Hence, total possible outcomes = 52
(5) Let E be the event of getting a spade.
There are 13 cards in each suit. {2,3,4,5,6,7,8,9,10,J,Q,K,A}
Hence, number of favourable outcomes = 13
Therefore, the probability of getting a spade is

Total number of cards in a well-shuffled deck = 52
Hence, total possible outcomes = 52
(4) Let E be the event of getting the jack of hearts
Hence, the number of favourable outcomes = 1
Therefore, the probability of getting the jack of hearts is

Total number of cards in a well-shuffled deck = 52
Hence, total possible outcomes = 52
(3) Let E be the event of getting a red face card.
Face cards: (J, Q, K) of hearts and diamonds
Hence, number of favourable outcomes = 3x2 = 6
Therefore, the probability of getting a red face card is

Total number of cards in a well-shuffled deck = 52
Hence, total possible outcomes = 52
(2) Let E be the event of getting a face card.
Face cards: (J, Q, K) of each four suits
Hence, number of favourable outcomes = 12
Therefore, the probability of getting a face card is

Total number of cards in a well-shuffled deck = 52
Hence, total possible outcomes = 52
(1) Let E be the event of getting a king of red colour.
There are only red colour kings: Hearts and diamonds
Hence, number of favourable outcomes = 2
Therefore, the probability of getting a king of red colour is

Possible outcomes when a die is thrown = {1,2,3,4,5,6}
Number of possible outcomes once = 6
(iii) Let O be the event of getting an odd number.
Odd numbers on the die are = {1,3,5}
Number of favourable outcomes = 3
Therefore, the probability of getting an odd number is

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