How did the industrial revolution affect cultural hearths?

What is the value of n in the given statement 8n< 40

Match the following terms and definitions a region in arkansas defined by the arkansas river in the western part of the state answer 1 a thoroughly dissected area with steep valley walls and narrow floors answer 2 a geographical region of a country or state answer 3 the friendly and generous reception and entertainment of guests, visitors, or strangers answer 4 the branch of knowledge concerned with the production, consumption, and transfer of wealth answer 5 statistical data relating to the population and particular groups within it answer 6 a mountain range in west central arkansas and southeastern oklahoma answer 7 travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours answer 8 answer all parts of the question.

If scientists only detect p waves in a certain layer of earths interior what does that tell us?