Given below are the **Class 9 Maths** Important Questions for Probability

a. Concepts questions

b. Calculation problems

c. Multiple choice questions

d. Long answer questions

e. Fill in the blanks

f. Link type comprehension

a. Concepts questions

b. Calculation problems

c. Multiple choice questions

d. Long answer questions

e. Fill in the blanks

f. Link type comprehension

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

$1 - \frac {7}{24} = \frac {17}{24} = 0.71$ (rounded to 2 decimal places)

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

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

a. True , P= $\frac {20}{100}=.2$

b. True , P= $\frac {(40+12+28)}{100}=.8$

c. False ,P= $\frac {28}{100}=.28$

d. True. P= $ \frac {28}{100}=.28$

The probability of the events lies between

a. -1 ≤ p ≤ 1

b. 0 ≤ p ≤ 1

c. -1 ≤ p ≤ 0

d. -1 < p ≤ 1

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

4.97 5.05 5.08 5.03 5.00 5.06 5.08 4.98 5.04 5.07 5.00 5.12

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

of flour

a. $\frac {1}{12}$

b. $\frac {7}{12}$

c. $\frac {2}{3}$

d. None of these

No of bags having weight more than 5 kg=8

Total =12

So $P= \frac {8}{12} = \frac {2}{3}$

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:

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

a. $.06$

b. $.08$

c. $.04$

d. None of these

Around 240 household are there satisfying the condition

So $P= \frac {240}{4000}=.06$

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. $.3$

Around 760 household are there satisfying the condition

So $P= \frac {760}{4000}=.19$

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

Around 980 household are there satisfying the condition

So $P= \frac {980}{4000}=.245$

In the above question, Find the probability of a household having no mobile set at all?

a. $ \frac {3}{400}$

b. $ \frac {1}{400}$

c. $ \frac {1}{200}$

d. None of these

Around 30 household are there satisfying the condition

So $P= \frac {30}{4000}= \frac {3}{400}$

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

As no household exists like than, So probability is 0

**Notes**-
**NCERT Solutions & Assignments**

Class 9 Maths Class 9 Science