Admission Tests Related Exams
GMAT Exam
Consider all positive integers a, 6, and c such that 135 is a factor of each of the expressions 15a, 254, and 30c. What is the greatest common factor of all possible sums. a+b+c?
Archaeologists have excavated two ancient sites, Site A and Site B, each containing bowls and dishes. A third site containing similar vessels (bowls and dishes), Site C, Is known to have existed but has not yet been located. The vessels have been dated to three successive 40-vear-long time periods (Mil).
The dishes that were found are small and plain and were made primarily for everyday use. For each site, the average population at the site for a period is known to be roughly proportional to the number of dishes found that were dated to that period.
The bowls are more elaborate, decorated In either a curvy or a rectilinear style. They were made primarily for ritual use. The numbers of bowls found indicate the level of wealth of the site's inhabitants during the period to which the bowls were dated (with greater numbers indicating greater wealth).
Documents found at Sites A and B establish that exactly 18 of the dishes found at Site A were manufactured at Site C; otherwise, all of the vessels were made at the sites where they were found.


For each of the following statements, select Yes if the Information provided supports the statement. Otherwise, select No.

Welleby’s Plan
The water In the underground water table beneath the town of Welleby is moderately saline— 20,000millkjrarns of salt per liter of water (mg/L), or roughly half as saline as ocean water. To lower the level of the water table and thus prevent agricultural land from being inundated with salt water, the town plans to pump water from the table at a rate of 450kiloliters per day (kL/day) into a large shallow pond, allowing much of the water to evaporate. The town plans to divert 10percent of the water pumped from the water table to supplement Us supply of drinking water, which Is currently piped In from great distances. Due to the water's supply, the town intends to construct a desalination plant to treat the diverted water for use as drinking water.
Desalination Types

Comparison
Welleby is deciding among the following three desalination methods.
Reverse Osmosis (RO): Water Is pushed through a membrane, leaving salts behind. RO systems can handle a large range of water flow rates and use relatively little energy. However, RO membranes are expensive and must be replaced every 2 to 5 years. There is also a possibility that bacteria can grow on the membrane. Introducing tastes and odors Into the desalinated water.
Multi-Effect Distillation (MED): Saline water Is heated to produce water vapor, from which Is condensed potable fresh water. This process requires large amounts of energy, regardless of the salinity of the source water. It becomes more cost effective as water volumes increase.
Electrodialysis (ED): Electricity is used to selectively move salts through a membrane. Consumption of energy Is directly proportional to the salinity of the water to be treated, so with higher salinities the process rapidly becomes more costly than other methods. ED membranes need to be replaced every 7 to 10years.
Based on the information provided, which one of the following benefits to Welleby is most likely to result from Its building a desalination plant?