Question

4. A swimming pool is 15 m in length, 12 m in breadth and 2 m in depth. Find the cost of cementing
the floor and walls at the rate of 15 per sq. m.
5. Find the area of the base of a box of height 4 cm and lateral surface area 120 cm2 if its length is​

Answer 1

Step-by-step explanation:

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Answer 2

Answer :-

Given ,

Length of pool (l)=15m

Breadth of pool (b)=12m

Height of pool (h)=2m

Now,

Area of floor =l×b

=15×12

$= 180 {m}^{2}$

Area of walls

=2h(l+b)

=2×2(15+12)

=4×27

$= 108 {m}^{2}$

Total area =108+180

$= 288 {m}^{2}$

Cost of cementing = Rs.15 per square meter

Therefore,

Cost of cementing the floor and wall of pool

=15×288

=Rs.4320

$so \: the \: cost \: of \: cementing \: is \: 4320.$

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2) Let l and b be the length and breadth of box.

Therefore,

l=2b

Given -

Height of box (h)=4cm

Lateral surface area of box =120cm^2

As we know that,

Lateral surface area of cuboid =2h(l+b)

∴2×4(2b+b)=120

$= 3b = \frac{120}{8}$

$b = \frac{15}{3}$

⇒5cm

Therefore,

Length of box =l=2b=2×5

=10cm

Therefore,

Area of base of box

=l×b

=10×5

$= 50 {cm}^{2}$