Question

do it fasttt kal exam hai​

Answer 1

$\large{\underline{\underline{\pink{\textbf{Given:-}}}}}$

• ✒ Outer Diameter of Hemispherical Bowl = 17cm
• ✒ Inner Diameter of Hemispherical Bowl = 15cm
• ✒ Rate of polishing = 25paise/cm²

$\large{\underline{\underline{\pink{\textbf{Find:-}}}}}$

• ✑ Cost of polishing it.

$\large{\underline{\underline{\pink{\textbf{solution:-}}}}}$

❍ Outer Curved Surface Area:

• ➮ R = D/2
• ➮ R = 17/2cm

Now, using

➠ Curved Surface area of Hemisphere = 2πr²

✏ Outer Curved Surface area = 2πR²

where,

• π = 22/7
• R = 17/2cm

Substituting these values

⟹ Outer Curved Surface area = 2πR²

⟹ Outer Curved Surface area = 2×22/7×(17/2)²

⟹ Outer Curved Surface area = 44/7×289/4

⟹ Outer Curved Surface area = 12716/28

⟹ Outer Surface area = 454.142(approx.) cm²

⟹ Outer Curved Surface area = 454.14 cm²

❍ Inner Curved Surface Area:

• ➮ r = d/2
• ➮ r = 15/2cm

Now, again using

➠ Curved Surface area of Hemisphere = 2πr²

✎ Inner Curved Surface area = 2πr²

where,

• π = 22/7
• r = 15/2cm

Substituting these values

↬Inner Curved Surface area = 2πr²

↬Inner Curved Surface area = 2×22/7×(15/2)²

↬Inner Curved Surface area = 44/7×225/4

↬Inner Curved Surface area = 9900/28

↬Inner Curved Surface area = 353.571(approx.) cm²

↬Inner Curved Surface area = 454.14 cm²

Now, using

❏ Area of brim = πR² - πr²

where,

• π = 22/7
• R = 17/2cm
• r = 15/2cm

• Substituting these values •

• ❐ Area of brim = πR² - πr²
• ❐ Area of brim = π(R² - r²)
• ❐ Area of brim = 22/7{(17/2)² - (15/2)²}
• ❐ Area of brim = 22/7(289/4 - 225/4)
• ❐ Area of brim = 22/7(289-225/4)
• ❐ Area of brim = 22/7(64/4)
• ❐ Area of brim = 1408/28
• ❐ Area of brim = 50.285(approx.) cm²
• ❐ Area of brim = 50.28 cm²

Now,

• ➺ Area to be polished = outer C.S.A+Inner C.S.A+Area of brim
• ➺ Area to be polished = 454.14+454.14+50.28
• ➺ Area to be polished = 958.56 cm²

Cost of polishing:-

⟶ Cost of polishing = 25 × 958.56

⟶ Cost of polishing = 23964paise

•Hence, Cost of polishing the Hemispherical Bowl is 23964paise

Answer 2

Step-by-step explanation:

Given :-

The outer and inner diameters of a hemispherical bowl are 17 and 15 cm respectively..

To find:-

Cost at 25 paise per m^2 .

Solution:-

Total area Covered

=[2π(17)^2+2π(15)^2]

=4π(17^2-15^2)] cm^2

=(578π+450π+64π)cm^2

=1092×22/7 cm^2

=3432cm^2

Cost=>3432×0.25

Cost=>Rs.4858.

hope it will help you dear