Question

a man is painting hemisphere alarm at the rate of rupees 15 per square meta find total cost of painting it if diameter of alom is 14 cm



plz type answer fastly it's very urgent​

Answer 1

Answer :-

• Total Cost of painting = 46.2 Rs

Given :-

• Diameter of Alarm = 14 cm
• Rate of painting = 15 Rs / m²

To Find :-

• Total Cost of painting = ?

Explanation :-

As above given, a man is painting a Hemispherical Alarm and we know that alarm will be placed on a wall. It means we have to paint only upper side of the alarm. Hence, we will find the CSA of Alarm.

Finding Radius of Alarm,

$\pink { \boxed { \bf \bigstar \: Radius \: (r) = \dfrac{Diameter}{2} \: \bigstar }}$

$\rm : \: \leadsto \dfrac{14}{2} \: cm$

$\gray { \bf : \: \leadsto 7 \: cm }$

Finding CSA of Alarm,

$\green { \boxed { \bf \bigstar \: CSA \: of \: Alarm = 2 \pi r^2 \: \bigstar }}$

$\rm : \: \leadsto 2 \pi r^2 = CSA \: of \: Alarm$

$\rm : \: \leadsto 2 \times \dfrac{22}{7} \times (7)^2$

$\rm : \: \leadsto 2 \times \dfrac{22}{7} \times 7 \times 7$

$\rm : \: \leadsto 2 \times 22 \times 7$

$\rm : \: \leadsto 44 \times 7$

$\blue { \bf : \: \leadsto 308 \: cm^2 \quad OR \quad 3.08 \: m^2 \: \: \star}$

Now, Finding Cost of painting the Alarm,

$\rm : \: \leadsto Cost \: of \: Painting \: 1 \: m^2 = \bold{15 \: R_S}$

$\rm : \: \leadsto Cost \: of \: Painting \: 3.08 \: m^2,$

               $\rm = 3.08 \times 15 \: R_S$

                $\red { \underline { \boxed { \bf \star \: = 46.2 \: R_S \: \star }}}$

Hence, the cost of painting the Hemispherical Alarm is 46.2 Rs.