Question

the conference hall of a school is 15 m wide and has a door at a comer .A teacher enters at 8.00 am through the door and makes 10 rounds along the 15 m wall back and forth during the period and finally leaves the class-room at 9.30 a.m. through the same door. Compute his average speed and average velocity​

Answer 1

(a)We have,

Length = 14 m.

Breadth = 8 m.

Height = 4 m.

(i) Area of 4 walls of the hall = 2h(l + b)

                                              = 2 * 4(14 + 8)

                                              = 176 m²

(ii)

Area of 1 door = 2 m².

Area of 1 window = 1.5 m²

∴ Area of 4 windows

= 4 * 1.5

 = 6 m²

∴ Area of four walls to be painted = [176 - (2 + 6)]

                                                        = 176 - 8

                                                        = 168 m²

Given that one litre is enough for covering 18 m².

Then, cost of painting 168 m² = (168/18)

                                                 = 28/3

                                          = 9(1/3) litres.

(b)

1 litre = 225

9(1/3) litres = ?

⇒ (225 * 28)/3

⇒ 6300/3

⇒ 2100.

Therefore, cost of painting is 2100