This diagram shows how loud certain frequencies must be in
order for people of different ages to hear them. the needed
intensity is called the "hearing level."
according to the graph, what is the maximum age at which a
4000 hz sound wave with an intensity of 20 db would be
heard?
hearing level (db)
55
60
65
70
500 hz
2000 hz
3,000 hz
4,000 hz
6,000 hz
70
20
30
60
40 50
age (years)
age (years)

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in tanzania, from a period slightly after the time that homo habilis was present in africa. these sites clearly were founded by homo erectus, the descendent species of homo habilis that migrated north, out of africa and into asia. homo erectus was known to have mastered fire, from ample evidence at sites in asia. there is no reason to attribute mastery of fire to homo ergaster, the descendent species of homo habilis that remained in africa.which of the following is an assumption on which the argument depends? (a) before their migration, homo erectus occupied african territory as far south as tanzania.(b) the strain of migration provided the selective pressure motivating homo erectus‘ mastery of fire.(c) homo ergaster would not have derived as much benefit from the mastery of fire as did homo erectus.(d) homo ergaster inherited all cultural knowledge from homo habilis, a species that did not have mastery of fire.(e) homo ergaster did not occupy regions as far south as tanzania until well after the time of these three sites.