# NCERT Class 9 Mathematics Probability Formative Assessment Board Sample Problems (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Link type comprehension**

**Question** 1

Twenty four people had a blood test and the results are shown below.

A, B, B, AB, AB, B, O, O, AB, O, B, A

AB, A, 0, O, AB, B, O, A, AB, O, B, A

(a) Construct a frequency distribution for the data.

(b) If a person is selected randomly from the group of twenty four people, what is the probability that his/her blood type is not O?

**Solution**

(a)

Class | Frequency |

A | 5 |

B | 6 |

AB | 6 |

O | 7 |

(b)

(Rounded to 2 decimal places)

True or False statement

**Question** 2

Over the past 100 working days, the number of defective bulbs produced by a machine is given in the following table:

No of Defective parts | 0 | 1 | 2 | 3 |

Days | 20 | 40 | 12 | 28 |

a) The probability that tomorrow output will be defect free is 2.

b) The probability that tomorrow output will have at least 1 defect is 8.

c) The probability that tomorrow output will have more then 2 defect is 30.

d) The probability that tomorrow output will have 3 defects is 28.

**Solution**

a) True

b) True,

c) False,

d) True.

**Multiple choice Questions**

**Question** 3

The probability of the events lies between

a)

b)

c)

d)

**Solution** (b)

**Question** 4

Twelve bags of wheat flour, each marked 5 kg, actually contained the following weights of flour (in kg) :

Find the probability that any of these bags chosen at random contains more than 5 kg of flour

a)

b)

c)

d) None of these

**Solution** (b)

No of bags having weight more than 5 kg = 7

Total

So

**Question** 5

A company selected 4000 households at random and surveyed them to find out a relationship between income level and the number of mobile sets in a home. The information so obtained is listed in the following table:

Monthly income | No of Mobile sets | |||

0 | 1 | 2 | Above2 | |

< 10000 | ||||

10000 - 14999 | ||||

15000 - 19999 | ||||

20000 - 24999 | ||||

25000 and above |

Find the probability of a household earning ₹ 10000 — ₹ 14999 per year and having exactly one mobile set

a) 06

b) 08

c) 04

d) None of these

**Solution** (a)

Around 240 household are there satisfying the condition

So

**Question** 6

In the above **Question**, find the probability of a household earning more than 25000 per year and having exactly 2 mobile set

a) 2

b) 19

c) 12

d) 3

**Solution** (b)

Around 760 household are there satisfying the condition

So

**Question** 7

In the above **Question**, find the probability of a household earning more than 25000 per year and having 2 or more mobile set

a) 245

b) 3

c) 1

d) None of these

**Solution** (a)

Around 980 household are there satisfying the condition

So

**Question** 8

In the above **Question**, find the probability of a household having no mobile set at all?

a)

b)

c)

d) None of these

**Solution** (a)

Around 30 household are there satisfying the condition

So p

**Question** 9

In the above **Question**, find the probability of a household having 3 mobile set and having income less than 10000

a) 1

b) 0

c) 24

d) None of these

**Solution** (b)

As no household exists like than, so probability is 0