Question

A wooden bookshelf has external dimensions as
follows: Height = 110 cm, Depth = 25 cm,
Breadth=85 cm (see Fig. 13.31). The thickness of
the plank is 5 cm everywhere. The external faces
are to be polished and the inner faces are to be
painted. If the rate of polishing is 20 paise per
cm and the rate of painting is 10 paise per
cm?
find the total expenses required for polishing and
painting the surface of the bookshelf.
Fig. 13.3
ercises are not from examination point of view.​

Answer 1

Answer:

hi follow mee A wooden bookshelf has external dimensions as

follows: Height = 110 cm, Depth = 25 cm,

Breadth=85 cm (see Fig. 13.31). The thickness of

the plank is 5 cm everywhere. The external faces

are to be polished and the inner faces are to be

painted. If the rate of polishing is 20 paise per

cm and the rate of painting is 10 paise per

cm?

find the total expenses required for polishing and

painting the surface of the bookshelf.

Fig. 13.3

ercises are not from examination point of view.

Answer 2

Direct explain karta hu :---

external h = 110cm

" d = 25cm

" b = 85cm

•°• external surface area = 2(hd+db+hb)

=> 2(2750+2125+9350)

=> 28450cm^2

•°• total cost to polish it @20p/cm^2 (question error) (should be square cm not only cm) = 20×28450p = 569000p or ₹5690

internal h = 110-(5+5) =100cm

" d= 25-(5+5) = 15cm

" b= 85 - (5+5) =75cm

•°• internal area = 2(hd+db+hb)

=> 2(1500+1125+7500)

=>20250cm^2

•°• total cost to paint @10p/cm^2 (same erorr) = 10×20250p =202500p or ₹2025

•°• total cost = ₹(5690+2025) = ₹7715 ans.

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