Question of Exercise 3

Probability of Class 12

Question

If A and B are two independent events such that and , then α is

 

Answer

Option 1

Option 2

Option 3 1

Option 4 none of these

Frequently Asked Questions

A man is known to speak the truth 3 out of 4 times

He throws a die and reports that it is a six. The probability that it is actually a six is

A: 3/8

B: 1/8

C: 1/4

D: 1/2

Solution:

Explanation:

Let R,S be the event that the man reports that is a six and the throw is a six respectively.  

P(R|S)= the probability that the man reports it is a six when it is a six = probability of speak truth =3/4

P(R|S')= the probability that the man reports it is a six when it is not a six = probability of not speak truth =1/4

P(S)= the probability that throw is six =1/6

P(S')= the probability that throw is not a six =1-1/6=6-1/6=5/6

Now we have to find the probability that the throw is actually six when the man reports it is a six i.e. P(S|R)

By the Bayes theorem,

 probability5

Final Answer:

Hence the correct option is (A).i.e 3/8

The number of millions in one crore are

A: 10

B: 20

C: 50

D: 100

 

Solution:

Explanation:

One crore is equal to 100 lakhs.

One million is equal to 10 lakhs.

Therefore,

1 crore = 100/10 million

⇒1 crore = 10 million

Final answer:

Hence, option A is correct.

The number of millions in one crore are 10.

 

 

How many days are there in x weeks x days

A: 7x2

B: 8x

C: 14

D: 7

Solution:

Explanation:

One week has 7 days.

Thus, weeks days has,

(7×x)+x=7x+x

=8x

Final answer:

Hence, option B is correct.

8x days are there in weeks days.

 

 

Thirty one crore fifty five lakh thirty

- two thousand eight hundred in numerals is written as

A: 31,55,32,800

B: 3,01,55,32,800

C: 3,15,05,32,800

D: 3,15,53,02,800

Solution:

Explanation:

Thirty one crore fifty-five lakh thirty-two thousand eight hundred can be expressed in the Indian system as,

30,00,00,000+1,00,00,000+50,00,000,+5,00,000+30,000+2,000+800+00+0

=31,55,32,800

Final answer:

Option A is correct, that is

Thirty one crore fifty - five lakh thirty - two thousand eight hundred in numerals is written as 31,55,32,800.

The LCM of two numbers is 495 and their HCF is 5

If the sum of the numbers is 100 then their difference is:

A: 10

B: 46

C: 70

D: 90

Solution:

Explanation:

The LCM of two numbers = 495

The HCF of two numbers = 5

Sum of the numbers = 100

Difference of the numbers = ?

Let one number be x and another number be 100 - x.

two numbers

Final answer:

The correct answer is option A, that is

The difference between those two numbers is 10.

 

 

Talk to Our counsellor