Question

A hall of size 4.5m* 3*2m is to be painted with colour the hall has two doors of size 60* 40*cm and 8 windows of size 15* 105cm find the cost of colour at the rate of RS 10per sq m . The floor and ceiling of the hall remains unpainted .

Answer 1

area of the hall =

$4.5 \times 3.2 = 14.4 {m}^{2}$

area of the doors =

$(0.6 \times 0.4 ) \times 2= 0.48{m}^{2}$

area of the windows =

$(0.15 \times 1.05) \times 8 = 1.26 {m}^{2}$

therefore,

area required =

$(14.4 - 0.48 - 1.26) {m}^{2} = 12.66 {m}^{2}$

cost of colouring per sq. m =Rs. 10

so, cost of colouring 12.66per sq. m =

$rs. \: (12.66 \times 10) = rs.126.6$

Answer 2

As we know that,

TSA of cuboid =2(l×b+b×h+h×l)

But here we have to subtract one side of the hall because we don't paint the floor and ceiling

So, formula will change likewise

Area of hall that will be painted={2(l×b+b×h+h×l)-2×l×b}

=2(b×h+h×l)

Here,

l=450cm,b=300cm,h=200cm(hall)

l=60cm,b=40cm(doors)

l=15cm,b=105 cm (windows)

=2(300×200+200×450)

=2(60000+90000)

=2(150000)

=300000cm^2

now i.e =30m^2

we have to subtract the area of doors and windows

Area of doors= 2×l×b

=60×40×2

=2400cm×2

=4800cm^2

now i.e=0.48m^2

Area of windows=8×l×b

=8×15×105

=8×1575

=12600cm^2

now i.e=1.26m^2

Area of Real hall= Area of hall-(Area of 2 doors +Area of 8 windows)

=30 - ( 0.48+1.26)

=30 - 1.74

=28.26m^2

Total Cost = Rate × Total amount

=10 ×28.26

= ₹282.6

=₹283(approx)

!!!!!! Hope it will help!!!!