CBSE Class 9 Maths - Surface Areas and Volumes - NCERT Exercise 13.2 (#cbseclass9Notes)

Surface Areas and Volumes

NCERT Exercise 13.2

Q1: The curved surface area of a right circular cylinder of height 14 cm is 88 cm². Find the diameter of the base of the cylinder.

Answer: Given, h = 14 cm,
curved, surface area (CSA) = 88 cm², r = ?
CSA  = 2πrh
⇒ 88 = 2 × (22/7) × r × 14
⇒ 88 = 44 × 2 × r
⇒ r = 88/88 = 1
∴ diameter = 2r = 2 cm


Q2: It is required to make a closed cylindrical tank of height 1 m and base diameter 140 cm from a metal sheet. How many square metres of the sheet are required for the same?.

CBSE Class 9 Maths - SURFACE AREAS AND VOLUMES (NCERT EXERCISE 13.1) (#cbsenotes) (#ncertsolutions)

SURFACE AREAS AND VOLUMES

Class 9 Maths 

NCERT EXERCISE 13.1

Q1: A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It is to be open at the top. Ignoring the thickness of the plastic sheet, determine :
(i) The area of the sheet required for making the box.
(ii) The cost of sheet for it, if a sheet measuring 1 m2 costs Rs 20.

Answer: Given,
l = 1.5 m,
b = 1.25 m,
h = 65 cm = 0.65 m

(i) ∵ the box is open at the top, it has only five faces.

Surface Area (SA) for five faces = lb + 2(bh + hl)

= 1.5 × 1.25 m² + 2 (1.25 × 0.65 + 0.65 × 1.5) m²
= 1.875 + 2 (1.7875) m² = 1.875 + 3.575
= 5.45 m²

(ii) Cost of 1 m² of the sheet = ₹ 20
∴ cost of 5.45 m² of the sheet = 20 × 5.45 m² = ₹ 109 (Answer)


Q2: The length, breadth and height of a room are 5m, 4m and 3m respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of Rs 7.50 per m².

Class 8/ Class 9 - Properties Of Quadrilateral Figures (Worksheet) (#CBSEClass8Maths) (#CBSEClass9Maths)

Properties Of Quadrilateral Figures

(Worksheet)

Question. Fill in the blanks (True or False) for the properties of the following figures:

Property	Parallelogram	Rhombus	Rectangle	Square
1. Both pairs of opposite sides are parallel and equal.	?	?	?	?
2. Both pairs of opposite angles are equal.	?	?	?	?
3. Diagonals bisect each other.	?	?	?	?
4. Diagonals are equal.	?	?	?	?
5. Each angle is 90°	?	?	?	?
6. Diagonals intersect at right angles.	?	?	?	?
7. All sides are equal.	?	?	?	?

CBSE Class 9 - Mathematics - CH 11 - Constructions - Very Short Questions and Answers (#CBSEClass9Notes)

Constructions

Very Short Questions and Answers
Based NCERT Class 9 Mathematics Chapter


Q1: With the help of ruler and compass, which of the following angles can be constructed?

(a) 35°
(b) 40°
(c) 37.5°
(d) 15°


Answer:  37.5° and 15° angles can be constructed using a ruler and a compass.


Q2(NCERT Exemplar): With the help of a ruler and a compass it is not possible to construct an angle of :

(A) 37.5°
(B) 40°
(C) 22.5°
(D) 67.5°

Class 9 - Mathematics - Ch10 - Circles (Worksheet) (#CBSENotes)

Circles 

CBSE Class 9 - Mathematics - Chapter 10

Worksheet 

Fill In the blanks

1. A _____ is a set of points in a plane, each one of which is at a constant distance from a fixed point in the plane.


2. A line segment joining two points on a circle is called the ______ of the circle.


3. A line which meets a circle in two points is called a ________ of the circle.


4. A chord passing through the center of the circle is called a ________ of the circle.

CBSE Class 9 - Mathematics - Probability - Problems and Solutions

Probability

Problems and Solutions (NCERT Exemplar Answers)

Problem 1: Two dice are thrown simultaneously 500 times. Each time the sum of numbers appearing on their top is noted and recorded as given in the following table:

Sum	2	3	4	5	6	7	8	9	10	11	12
Frequency	14	30	42	55	72	75	70	53	46	28	15

If the dice are thrown once more, what is the probability of getting a sum
(i) 3
(ii) more than 10
(iii) less than 5 or equal to 5
(iv) between 8 and 12

Solution: Click here to see the solution.


Problem 2: Here is an extract from a mortality table:

Age(in years)	60	61	62	63	64	65
Number of persons surviving out of sample of one million	16090	11490	8012	5448	3607	2320

(i) Based on this information, what is the probability of a person 'aged 60' of dying within a year?

(ii)What is the probability that a person 'aged 61'will live for 4 years?

CBSE Open Text Based Assessment (OTBA) for classes IX & XI, 2017 is Available

Open Text Based Assessment (OTBA) 

For classes 

IX & XI  2017

Available Now

OTBA Material for Class 9 and Class 11 for this session (2016-2017) is available at CBSE website. Here are the links to download the pdfs.

Open Text Material for Class IX

Subject- English
Subject- Hindi
Mathematics - English - Hindi
Science - English - Hindi
Social Science - English - Hindi

CBSE Class 9 - Maths - Quadrilaterals (Questions and Answers)

Quadrilaterals 

Class 9 NCERT Exemplar Problems and Solutions

Question 1: If angles A,B,C and D of a quadrilateral ABCD, taken in order, are in the ratio 3:7:6:4 then ABCD is a trapezium. Is this statement true? Give reason for your answer.

Solution: Since, the angles are in the ratio 3:7:6:4,

Let these angles be 3x,7x,6x and 4x.

∵Since sum of angles of a quadrilateral is 360°,

∴3x+7x+6x+4x=360°

⇒ 20x=360°

⇒x=18°

∴The angles are:
   ∠A=3×18°=54°,
  ∠B=7×18°=126°,
  ∠C=6×18°=108° and
 ∠D=4×18°=72°

Since ∠A+∠B=54°+126°=180°. Thus, the sum of co-interior angles is 180°formed by lines AD,BC and transversal AB, ∴, AD∥BC.

So,ABCD is a trapezium.

Hence, the given statement is true.

Class 9 - Maths - Quadrilaterals - Important Points to remember (#CBSE-Notes)

Quadrilaterals 

Important Points to remember

Based on Class 9 NCERT Chapter on Quadrilaterals

Simple Classification of Quadrilaterals.
For detailed version check at wikipedia

① A simple closed figure bounded by four line segments is called quadrilateral.

② The sum of (interior) angles of a quadrilateral is 360°- Angle Sum Property of Quadrilateral

③ A quadrilateral in which one pair of opposite sides is parallel is called trapezium.

④ A quadrilateral in which both pairs of opposite sides are parallel is called parallelogram.

⑤ If one of the angles of a parallelogram is right angle then it is a rectangle.

⑥ If all sides of a quadrilateral are equal then it is called rhombus.

CBSE Class 9, 10, 11, 12 - Mathematics - Know about Special Constants

Know about Special Constants

Change is the only constant in our lives. However, there are constants or constant numbers that are frequently used in the domains of Science, Mathematics, Economics etc.

Do you know what is golden ratio?

What is the value of Pi?

What are transcendental numbers?

What's the value of cube root of 2?

CBSE - Class 6-12 - Mathematics - Important Formulas

Mathematics - Important  Formulas 

eduvictors.com has added a new section "Mathematics" and has compiled important formulas on different topics.

Here is the list of Mathematics formulas:

1. Algebra Formulas

⓵ Polynomials
⓶ Fractions
⓷ Algebraic Identities
⓸ Exponents
⓹ Roots

CBSE Class 9 - Mathematics- SA1- Sample Question Paper (2016)

CBSE Class 9 - Mathematics- SA1- Sample Question Paper (2016) 

CBSE Class 9 - SA1 - Maths - Lines and Angles (Questions and Answers)

Lines and Angles 

(Questions and Answers)

 

Here follows few questions that have asked in previous examination papers.

CBSE Class 9 - Maths - SA1 - Polynomials (Problems Usually Asked)

Polynomials 

Problems Asked in SA1 Papers

You may download this post as pdf.
Q1: Solve the following question using factor theorem.



Q2:

CBSE Class 9 - Lines and Angles (Worksheet-2)

Lines and Angles (Worksheet-2)

Question: Fill in the blanks

1. Three or more points said to be __________ if there is a line which contains all these points.


2. Two lines are called ___________ lines, if they have common point.


3. Three or more lines intersecting at the same point are called as ____________ lines.


4. An angle whose measure is less than 90° is called _________ angle.


5. An angle whose measure is 90° is called _________ angle.


6. An angle whose measure is more than 90° but less than 180°, is called _______ angle.

CBSE Class 9 - Maths- SA2- Sample Question Paper (2016)

CBSE Class 9 - Maths- SA2- Sample Question Paper (2016) 

CBSE Class 9 Maths - SA2 - Sample Question Paper (2012)

CBSE Class IX - Maths- SA2- Sample Question Paper (2012) 
The sample paper is based on old pattern, still it is good for practice.

CBSE Class 9 - Maths - SA1 -Sample Question Paper (2015-16)

CBSE Class 9 - Maths - Sample Question Paper
Paper sent by one of the reader. Good for practice.

CBSE Class 9 - Maths SA1 - Sample Question Paper (2010-11)

CBSE Class 9 - Maths - Sample Question Paper
The paper is based on old pattern MCQs have been replaced by Very Short Questions. Still helpful.

CBSE Class 9 - Maths - Number Systems (Very Short Questions and Answers)

NUMBER SYSTEMS 

Very Short Q & A

Q1: Categorize the following numbers as
(i) Natural Numbers
(ii) Whole Numbers
(iii) Integers

(iv) Rational Numbers

7, 3/2, 0, 2, -9/5, 1/4, -8

Answer:
(i) Natural Numbers {2, 7}

(ii) Whole Numbers {0, 2, 7}

(iii) Integers {-8, 0, 2, 7} 

(iv) Rational Numbers {-8, -9/5, 0, 1/4, 3/2, 2, 7}

Q2: What is the rational number which does not have reciprocal?

Answer: 0 (zero)

Q3: Write the greatest negative integer.

Answer: -1

Q4: Name the smallest natural number.