Question

A homeowner purchases insulation for her attic rated at R-15. She wants the attic insulated to R-30. If the insulation she purchased is 10 cm thick, what thickness does she need to use

Answer 1

The thickness of insulation required to achieve an R-value of 30 can be calculated using the formula R = d/k. In this case, the homeowner needs to use insulation with a thickness of 20 cm to achieve the desired R-value.

Step-by-step explanation:

The thickness of insulation required to achieve the desired R-value can be calculated using the equation: R = d/k, where R is the desired R-value, d is the thickness of the insulation, and k is the thermal conductivity of the material. In this case, the homeowner wants to achieve an R-value of 30 and has already purchased insulation with an R-value of 15. We can set up the equation as follows:

• 30 = d/k, where R-value required is 30
• 15 = 10 cm / k, where R-value of the purchased insulation is 15

To find the thickness of insulation required, we can rearrange the equation and solve for d:

• d = R * k, where R is the desired R-value

Substituting the known values:

• d = 30 * (10 cm / 15)
• d = 20 cm

Therefore, the homeowner would need to use insulation with a thickness of 20 cm to achieve an R-value of 30.

Answer 2

she need to use 20 cm thick

Step-by-step explanation:

given data

wants the attic insulated = R-30

purchased = 10 cm thick

solution

as per given we can say that

10 cm is for the R 15

but she want for R 30

so

R 30 thickness =
`(30)/(15) * 10`

R 30 thickness = 20 cm

so she need to use 20 cm thick