GMAT Exam Dumps : Graduate Management Admission Test (2022)

In 90 percent of the commercial airline accidents last year, one or another of a group consisting of only 18 percent of the world's commercial airlines was involved. Since the other 82 percent of airlines were generally flying the same types of airplanes as the accident-prone airlines, significant differences in safety procedures must have been responsible for these differences In safety records.

Which of the following, if true about the world's commercial airlines last year, most seriously weakens the argument above?

For any data set, the proportion of data that lies within A" standard deviations of its mean is at least 1 - -K. The scores on a spelling test taken by 64 students have a mean of 74.0 and a standard deviation of 6.0. If t\$ the number of students who have scores greater than 62 and less than 86, and t\s as small as possible, what is the value of t?

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?