morya003 wrote:
Attachment:
Bookrack.PNG
Will the first 10 volumes of a 20-volume encyclopedia fit upright in the bookrack shown above?
(1) x = 50 centimeters.
(2) Twelve of the volumes have an average (arithmetic mean) thickness of 5 centimeters.
Target question: Will the first 10 volumes of a 20-volume encyclopedia fit upright in the bookrack shown above? Statement 1: x = 50 centimeters. We have no idea how THICK the first 10 volumes are.
They COULD each be 1 mm thick, in which case
the 10 volumes will easily fit in the 50 cm rack Or they COULD each be 1 km thick, in which case
the 10 volumes will NOT fit in the 50 cm rack Since we cannot answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: Twelve of the volumes have an average (arithmetic mean) thickness of 5 centimeters.We have no idea how wide the book rack is.
Statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined We have no info about the thickness of the 10 volumes to be placed in the rack.
Consider these two possible cases:
Case a: Each of the 12 volumes noted above in statement 2 are 5 cm thick. Two of those 5-cm-thick volumes are added to eight volumes that are each 1
mm thick. In this case,
the 10 volumes will easily fit in the 50 cm rack Case b: Each of the 12 volumes noted above in statement 2 are 5 cm thick. Two of those 5-cm-thick volumes are added to eight volumes that are each 1
km thick. In this case,
the 10 volumes will NOT fit in the 50 cm rack Since we cannot answer the
target question with certainty, the combined statements are NOT SUFFICIENT
Answer: E
Cheers,
Brent