The document RD Sharma Solutions Ex-25.1, (Part - 1), Probability, Class 9, Maths Class 9 Notes | EduRev is a part of the Class 9 Course RD Sharma Solutions for Class 9 Mathematics.

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**Q1. A coin is tossed 1000 times with the following sequence: ****Head: 455, Tail = :545. ****Compute the probability of each event**

**Answer:** It is given that the coin is tossed 1000 times. The number of trials is 1000

Let us denote the event of getting head and of getting tails be E and F respectively. Then

Number of trials in which the E happens = 455

So, Probability of

Similarity, the probability of the event getting a tail

**Q2. Two coins are tossed simultaneously 500 times with the following frequencies of different outcomes:**

**TWO HEADS: 95 times**

**ONE HEADS: 290 times**

**NO HEADS: 115 times**

**Find the probability of occurrence of each of these events**

**Answer:**

**Q3. Three coins are tossed simultaneously 100 times with the following frequencies of different outcomes:**

OUTCOME | NO HEAD | ONE HEAD | TWO HEAD | THREE HEAD |

FREQUENCY | 14 | 38 | 36 | 12 |

** If the three coins are tossed simultaneously again, compute the probability of:**

**1. heads coming up**

**2. heads coming up**

**3. At least one Head coming up**

**4. Getting more Tails than Heads **

**5. Getting more heads than tails**

**ANS:**

**1:** Probability of 2 Heads coming up

**2.** Probability of 3 Heads coming up

**3.** Probability of at least one head coming up

**4.** Probability of getting more Heads than Tails

**5. **Probability of getting more tails than heads

**Q4. 1500 families with 2 children were selected randomly, and the following data were recorded:**

No of girls in a family | 0 | 1 | 2 |

No of girls | 211 | 814 | 475 |

**If a family is chosen at random, compute the probability that it has:**

**1. No girl**

**2. 1 girl**

**3. 2 girls**

**4. At most one girl**

**5. More girls than boys**

**Answer**

**1.** Probability of having no girl in a family

**2.** Probability of having 1 girl in a family

**3.** Probability of having 2 girls in a family

**4.** Probability of having at the most one girl

**5.** Probability of having more girls than boys

**Q5. In a cricket match, a batsman hits a boundary 6 times out of 30 balls he plays. Find the probability that:**

**1. He hit a boundary**

**2. He did not hit a boundary.**

**Answer**

Number of times the batsman hits a boundary= 6

Total number of balls played= 30

Number of times the batsman did not hit a boundary= 30-6 = 24

**1.** Probability that the batsman hits a boundary

= 6/30

= 1/5

**2.** Probability that the batsman does not hit a boundary

= 24/30

= 4/5

**Q6. The percentage of marks obtained by a student in the monthly unit tests are given below:**

UNIT TEST | I | II | III | IV | V |

PERCENTAGE OF MARK OBTAINED | 69 | 71 | 73 | 68 | 76 |

**Find the probability that the student gets**

**1. More than 70% marks**

**2. Less than 70% marks**

**3. A distinction**

**Answer:**

**1:** Let E be the event of getting more than 70% marks

No of times E happens=3

Probability(Getting more than 70%)

**2.** Let F be the event of getting less than 70% marks

No of times F happen = 2

Probability(Getting less than 70%)

**3.** Let G be the event of getting distinction

No of times G happen = 1

Probability(Getting distinction) =

**Q7. To know the opinion of the students about Mathematics, a survey of 200 students were conducted. The data was recorded in the following table**

Opinion | Like | Dislike |

Number of students | 135 | 65 |

**Find the probability that student chosen at random:**

**1. Likes Mathematics**

**2. Does not like it.**

**Answer**

**1. **Probability that a student likes mathematics

**2.** Probability that a student does not like mathematics

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