Question

Raju planned to stitch a cover for his two speaker boxes whose length, breadth and height are 35 cm, 30 cm and 55 cm respectively. find the cost of the cloth he has to buy if it costs ` 75 per sq.m.

Answer 1

surface area of both covers = 2×(CSA +1base)

=2×{2(l+b)h+ lb}

=2×{2(35+30)55+35×30}

=2×{130×55+1050}

=2×(7150+1050)

=2*8200

=16400 sqcm

=1.64 sqm

cost of cloth = 1.64×75= ₹24.60

Answer 2

Answer:

Rs. 123

Step-by-step explanation:

Since raju wants planned to stitch a cover for his two speaker boxes

He need to cover the lateral surface area of speaker and one base

length = 35 cm

breadth = 30 cm

height = 55 cm

Since speaker is in the shape of cuboid :

Lateral surface area of cuboid + one base = $2(l+b)h + lb$

l = length= 35 cm

b = breadth = 30 cm

h = height  = 55 cm

So, area of cloth used to stitch the cover of speakers = $2(35+30)55 + 35\times 30$

                                                                                        = $7150+1050$

                                                                                        = $8200cm^2$

Since there are 2 speakers so, area of cloth required fro 2 speakers :

$2 * 8200 cm^2$

$16400cm^2$

Now, 1 sq.cm. = 0.0001 sq.m.

So, 16400 sq.cm. = 0.0001 *16400 = 1.64 sq.m.

Since cost of 1 sq.m. = 75

So, cost of 1.64 sq.m.=75*1.64 = 123

Hence  the cost of the cloth he has to buy is Rs.123