Class 8 Maths Data Handling Linking Chances to Probability

Chances can be converted to probability by finding the chances of occurring of an event against all the possible outcomes.

 Experiment Outcome/Event Total possible outcomes Probability (single outcome/total possible outcomes) Tossing of a coin 1 (Heads) 2 (Heads or Tails) 1/2 Tossing of a coin 1 (Tails) 2 (Heads or Tails) 1/2 Rolling a Dice 1 6 (1,2,3,4,5 or 6) 1/6 Rolling a Dice 3 6 (1,2,3,4,5 or 6) 1/6 Rolling a Dice 6 6 (1,2,3,4,5 or 6) 1/6

 Problem: When a die is thrown, list the outcomes of an event of getting: (i) (a) a prime number (b) not a prime number (ii) (a) a number greater than 5 (b) a number not greater than 5 Solution: (i) (a) Outcomes of event of getting a prime number are 2, 3 and 5. (b) Outcomes of event of not getting a prime number are 1, 4 and 6. (ii) (a) Outcome of event of getting a number greater than 5 is 6. (b) Outcomes of event of not getting a number greater than 5 are 1, 2, 3, 4 and 5.

 Problem: Numbers 1 to 10 are written on ten separate slips (one number on one slip), kept in a box and mixed well. One slip is chosen from the box without looking into it. What is the probability of: (i) getting a number 6. (ii) getting a number less than 6. (iii) getting a number greater than 6. (iv) getting a 1-digit number. Solution: (i) Outcome of getting a number 6 from ten separate slips is one. Therefore, probability of getting a number 6 = 1/10 (ii) Numbers less than 6 are 1, 2, 3, 4 and 5 which are five. So there are 5 outcomes. Therefore, probability of getting a number less than 6 = 5/10 = 1/2 (iii) Number greater than 6 out of ten that are 7, 8, 9, 10. So there are 4 possible outcomes. Therefore, probability of getting a number greater than 6 = 4/10 = 2/5 (iv) One digit numbers are 1, 2, 3, 4, 5, 6, 7, 8 and 9 out of ten. Therefore, probability of getting a 1-digit number = 9/10

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