Question

36. The cost of painting the TSA of a cone at 5 paise/ cm is 35.20 / - . If its slant height
is 25 cm, then its volume is
a) 1223 cm
b) 1232 cm c) 1323 cm
d) 1332 cm
thon the yolume of the cube is​

Answer 1

✪AnSwEr

${\tt{\red{\underline{\large{Given}}}}}$

• Cost of painting TSA of cone= 5p/cm is 35.20
• slant height =25cm

${\sf{\green{\underline{\large{To\:find}}}}}$

• volume

${\sf{\pink{\underline{\Large{Explanation}}}}}$

• we know that

TSA of cone:-πr(r+l)

TSA of cone = total cost / p/cm

=>TSA of cone=3520/5

=>TSA of cone=704cm²

Now

TSA of cone:-πr(r+l)

___________________________

=>πr(r+l)=704

=>πr(r+25)=704

=>πr²+25πr=704

=>r²+25r=704 × 7/22

=>r²+25r=32×7

=>r²+25r=224

=>=>r²+25r-224=0

=>r²+32r-7r-224=0

=>r(r+32)-7(r+32)=0

=>(r+32)(r-7)

=>r=7,-32

___________________________

Taking + value of r

r=7cm

Now from Pythagoras Theorm

• getting h

r²+h²=l²

=>49+h²=625

=>h²=625-49

=>h²=576

=>h=24cm

Now volums of cone

Volume of cone = 1/3 πr²h

=>1/3 × 22/7 × 7×7 ×24

=>22×7×8

=>22×56

=>1232cm³

Option b is right

Answer 2

Hey User!

GIVEN THAT:

• Slant height (l) = 25 cm.

• Cost of painting TSA of a cone at 5 paisa/cm^2 = 35.20 = 3520 paisa

To find:

• Volume of the cone.

Formula used:

• TSA of cone = πr(l+r)

• Volume of cone = 1/3(π)(r^2)(h)

where

l is slant height of the cone

r is the radius of cone

h is the height of cone

Now, ATQ, we have

TSA of cone = 3520/5 = 704 cm^2...(1)

Using above formula, we get

πr(l+r) = 704

22/7*r*(25+r) = 704

r^2 +25r = 32*7

r^2 +25r - 224 = 0

r^2 +32r -7r -224 = 0

(r+32)(r-7) = 0

r = 7 or 32

Since, radius can't be negative.

So, r = 7 cm....(2)

Now, applying Pythagoras theorem in the cone, we get

l^2 = r^2 + h^2

25^2 = 7^2 + h^2

h ^2 = 576

h = 24 cm...(3)

So, volumne of the cone will be...

Volume = 1/3*22/7*(7^2)(24)

Volume = 22*7*8

Volume = 1232 cm^3.

So, the volume of the cone will be 1232 cm^3.

So, option b is correct.

Note:

• Unit of volume is always in unit^3 and area's unit is always in unit^2.
• Eg. cm^2 and cm^3.

Hope this helps