+91-8076753736 [email protected]

-->

Probability

Question

Wired Faculty App

The diameter of roller 1.5 m long is 84 cm. If it takes 100 revolutions to level a playground, find the cost of levelling this ground at the rate of 50 paise per square metre.

Solution

For roller

straight r equals fraction numerator 1.5 over denominator 2 end fraction space straight m space equals space 0.75 space straight m

h = 84 cm = 0.84 m

therefore

Curved surface area =

2 πrh

equals 2 cross times 22 over 7 cross times 0.75 cross times 0.84 equals space 3.96 space straight m squared

∴ Area of the ground levelled in 1 revolution = 3.96 m²∴ Area of the ground levelled in 100 revolutions
= 3.96 x 100 m² = 396 m²∴ Cost of levelling

equals straight र space 396 space cross times 50 over 100 equals space र space 198

Some More Questions From Probability Chapter

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

A cubical box has each edge 10 cm and another cuboidal box is 12.5 cm long, 10 cm wide and 8 cm high.

(i) Which box has the greater lateral surface area and by how much?

A cubical box has each edge 10 cm and another cuboidal box is 12.5 cm long, 10 cm wide and 8 cm high.

(i) Which box has the greater lateral surface area and by how much?

A small indoor greenhouse (herbarium) is made entirely of glass panes (including base) held together with tape. It is 30 cm long, 25 cm wide and 25 cm high.

(i) What is the area of the glass?
(ii) How much of tape is needed for all the 12 edges?

Parveen wanted to make a temporary shelter for her car, by making a box-like structure with tarpaulin that covers all the four sides and the top of the car (with the front face as a flap which can be rolled up). Assuming that the stitching margins are very small, and therefore negligible, how much tarpaulin would be required to make the shelter of height 2.5 m, with base dimensions 4 m × 3 m?

Mock Test Series

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation