## Surface Area and Volumes – Exercise 13.6 – Class IX

Assume π = 22/7 , unless stated otherwise. The circumference of the base of a cylindrical vessel is 132 cm and its height is 25 cm. How many litres of water can it hold? (1000 cm3 = 1l) Solution: The circumference of the base of a cylindrical vessel = 132 cm = 2πr ; h… Continue reading Surface Area and Volumes – Exercise 13.6 – Class IX

## Surface Area and Volumes – Exercise 13.5 – Class IX

A matchbox measures 4 cm × 2.5 cm × 1.5 cm. What will be the volume of a packet containing 12 such boxes? Solution: Volume of 1 match box = lbh [here, l = 4cm , b = 2.5cm, h = 1.5cm] = 4 x 2.5 x 1.5 = 15 cm3 Volume of 12 such… Continue reading Surface Area and Volumes – Exercise 13.5 – Class IX

## Surface Area and Volumes – Exercise 13.4 – Class IX

Assume π = 22/7 , unless stated otherwise. Find the surface area of a sphere of radius: (i) 10.5 cm (ii) 5.6 cm (iii) 14 cm Solution: (i) r = 10.5 cm Surface area of the sphere  = 4πr2 = 4 x 22/7 x (10.5)2 = 1386 cm2 (ii) r = 5.6 cm Surface area… Continue reading Surface Area and Volumes – Exercise 13.4 – Class IX

## Surface Area and Volumes – Exercise 13.3 – Class IX

Assume π = 22/7 , unless stated otherwise. Diameter of the base of a cone is 10.5 cm and its slant height is 10 cm. Find its curved surface area. Solution: r = 10.5/2 cm = 5.25 cm , l = 10 cm Curved surface area of the cone = πrl = 22/7 x 5.25… Continue reading Surface Area and Volumes – Exercise 13.3 – Class IX

## Surface Area and Volumes – Exercise 13.2 – Class IX

The curved surface area of a right circular cylinder of height 14 cm is 88cm2 . Find the diameter of the base of the cylinder. Solution: Given, h = 14 cm ; surface area = 88 cm2 Curved surface area of the cylinder = 2πrh 88 = 2 x 22/7 x r x 14 r… Continue reading Surface Area and Volumes – Exercise 13.2 – Class IX

## Surface Area and Volumes – Exercise 13.1 – Class IX

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… Continue reading Surface Area and Volumes – Exercise 13.1 – Class IX