If 48 cm of brick and 15 cm of fiberglass have the same r value,
both materials have the same density
both materials have the same insulating ability
both materials have the same conducting ability
both materials have the same mass

The r value of a material is that which is related to the amount of heat that can be transferred through it. From the given example above, we say that the amount of heat that can be transferred through 48 cm of brick is the same amount of heat that can be transferred through 15 cm of fiberglass. This means that both substances have the same insulating ability. The answer is the second choice. 

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