CBSE Class 9 Maths - Surface Areas and Volumes - NCERT Exercise 13.5 (#cbsenotes) (#ncertsolutions)

Surface Areas and Volumes 

NCERT Exercise 13.5

Q1: A matchbox measures 4 cm × 2.5 cm × 1.5 cm. What will be the volume of a packet containing 12 such boxes?

Answer: Given, l = 4 cm, b = 2.5 cm, h = 1.5 cm
Volume of 1 matchbox = lbh
= 4 × 2.5 × 1.5 cm3 = 15 cm³
Volume of 12 matchboxes = 15 × 12  = 180 cm³ (Answer)


Q2: A cuboidal water tank is 6 m long, 5 m wide and 4.5 m deep. How many litres of water can it hold? (1 m³ = 1000 l)

Answer: Given,  l = 6 m, b = 5 m, h = 4.5 m
Volume of the tank = lbh
= 6 × 5 × 4.5 = 135 m³
= 135 × 1000 litres = 1,35,000 litres (Answer)

CBSE Class 10 - English (Communicative)- Sample Question Paper (2016-17)

CBSE Class 10 - SA2 - English (Communicative)- Sample Question Paper (2016-17) 

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CBSE Class 9 - Maths - Surface Areas and Volumes (NCERT Ex 13.4) (#cbseclass9notes)

Surface Areas and Volumes - Spheres

(NCERT Ex 13.4)

Q1: Find the surface area of a sphere of radius 
(i) 10.5 cm
(ii) 5.6 cm
(iii) 14 cm

Answer:
(i) r = 10.5 cm
Surface area of the sphere = 4πr²
= 4 × (22/7) × (10.5)²
  = 1386 cm² (Answer)

(ii) r = 5.6 cm
Surface area of the sphere = 4πr²
= 4 × (22/7) × (5.6)²
= 394.24 cm² (Answer)

(iii) r = 14 cm
Surface area of the sphere = 4πr²
= 4 × (22/7) × 14 × 14
= 2464 cm² (Answer)


Q2: Find the surface area of sphere of a diameter :
(i) 14 cm
(ii) 21 cm
(iii) 3.5 m

CBSE Class 12 - English (Elective)- Marking Scheme of Sample Question Paper (2016-17)

CBSE Class 12 - English (Elective)- Marking Scheme of Sample Question Paper (2016-17) 


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CBSE Class 9 - Maths - Surface Areas and Volumes - NCERT Ex 13.3 (#cbsenotes)

Surface Areas and Volumes

EXERCISE 13.3

Q1: Diameter of the base of a cone is 10.5 cm and its slant height is 10 cm. Find its curved surface area.

Answer: Given r = 10.5/2 = 5.25 cm, l = 10 cm.

Curved surface area (CSA) of the cone = πrl
= (22/7) × 5.25 × 10  = 165 cm² (Answer)



Q2: Find the total surface area of a cone, if its slant height is 21 m and diameter of its base is 24 m.

Answer: Given, l = 21m, r = 24/2 = 12 m
TSA (cone) = πr(l + r)
= (22/7) × 12 (21 + 12)
= 1244.57 m² (Answer)

CBSE Class 12 - English (Elective)- Sample Question Paper (2016-17) (#cbsepapers)

CBSE Class 12 - English (Elective)- Sample Question Paper (2016-17) 


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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?.