Question of Solved Question

Probability of Class 9

Question

A factory manufacturing car batteries made a survey in the filed about the life of these batteries. The data obtained is as under :

Life time          (in months)

Less than 24

24 to 36

36 to 48

More than 48

Total number of batteries

Frequency or the number of batteries

40

220

540

200

1000

A battery of this company is put in a car, what is the probability that
(i) the battery will last for more than 36 months?

(ii) the battery will last for less than 48 months ?

(iii) the battery will last for 36 to 48 months?

 

Frequently Asked Questions

Simplify the following expressions

(√(5) + √(2))2

 

Solution:

Explanation:

 

Simplify

Which of the following rational numbers lies between 0 and - 1

A: 0

B: - 1

C: -1/4

D: 1/4

 

Solution:

Explanation:

0 and 1 cannot be found between 0 and 1.

In addition,0= o/4  and -1= -4/4

We can see that -1/4 is halfway between 0 and -1.

Final Answer:

Hence, the correct option is (c) -1/4

 

Prove that the diagonals of a parallelogram bisect each other

Solution:

Explanation:

We must show that the diagonals of the parallelogram ABCD cross each other.

OA = OC & OB = OD, in other words.

Now AD = BC [opposite sides are equal] in ΔAOD and ΔBOC.

[alternative interior angle] ∠ADO = ∠CBO in ΔAOD and ΔBOC.

Similarly, ∠AOD = ∠BOC by ΔDAO = ΔBCO (ASA rule)

As a result, OA = OC and OB = OB [according to CPCT].

according to CPC

Final Answer:

Hence, it is prove that the diagonals of a parallelogram bisect each other.

 

What is total surface area of sphere

Solution:

Explanation:

  • The radius of the sphere affects the formula for calculating the sphere's surface area. 
  • If the sphere's radius is r and the sphere's surface area is S.
  • The sphere's surface area is therefore stated as Surface Area of Sphere 4πr2, where ‘r’ is the sphere's radius.
  • The surface area of a sphere is expressed in terms of diameter as S=4π(d/2)2, where d is the sphere's diameter.

Final Answer:

Thus, total surface area of sphere is =4πr2.

 

Fill in the blanks If two adjacent angles are supplementary

 they form a __________.

Solution:

Explanation:

  • If the non-common sides of two angles form a straight line, they are called linear pair angles. 
  • The sum of the angles of two linear pairs is  degrees.
  • If the total of two angles is  degrees, they are called supplementary angles.

Final Answer:

A linear pair is formed.

 

Talk to Our counsellor