In 1960’s studies of rats, scientists found that crowding increases the number of attacks among the animals significantly. But in recent experiments in which Rhesus monkeys were placed in crowded conditions, although there was an increase in instances of “coping” behavior – such as submissive gestures and avoidance of dominant individuals – attacks did not become any more frequent. Therefore it is not likely that, for any species of monkey, crowding increases aggression as significantly as was seen in rats.

Which of the following, if true, most strengthens the argument?

Scientist: Cross-sections of stalactites---calcite formations deposited on cave ceilings by seeping water-can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. We often found that when-according to these cross-sections- drought occurred in a particular area, it coincided with the collapse of an ancient society in that area. I hypothesize that drought reduced agricultural productivity in these areas thereby leaving these societies without the resources needed to handle internal stresses and external threats.

Which of the following, if true, would most weaken the support for the scientist's hypothesis?

Even though vegetable meal is nutritious to fish and less costly to use than anchovy meal, most fish farmers feed their fish only anchovy meal because fish prefer its taste and consequently gain weight faster. Farmed fish would gain weight faster still on a diet consisting of a new seafood product, butthis diet's advantages do not compensate for its additional cost . Nevertheless,   the product's developers predict that their product will be a commercially successful food for farmed fish .

Which of the following, if true, most helps to justify the developer's prediction?

For years the beautiful Renaissance buildings in Palitito have been damaged by exhaust from the many tour buses that come to the city. There has been little parking space, so most buses have idled at the curb during each stop on their tour, and idling produces as much exhaust as driving. The city has now provided parking that accommodates a third of the tour buses, so damage to Palitito's buildings from the buses' exhaust will diminish significantly.

Which of the following, if true, most strongly supports the argument?

If , then y=?

In the time taken by Morton to take 4 steps, Lindsey takes 5 steps. If Morton's three steps are equal to Lindsey's four steps and Lindsey's speed is 7.5 miles/hour, what is Morton's (approximate) speed?

How many positive integers less than 20 can be expressed as the sum of a positive multiple of 2 and a positive multiple of 3?

If the average weight of 8th, 9th and 10th class is in the ratio of a:b:c and the number of students in class 8th, 9th and 10th is in the ratio of x:y:z, then the average weight of all the three classes considered together is

If a and b are consecutive positive integers such that a² is divisible by 25 and b² is divisible by 63, which of the following is the greatest integer that must be a factor of ab ?

Orhan's blood glucose level decreased by p% during the first week of therapy. After two weeks, his blood glucose level was 4p% lower than its initial value. By what percent did his blood glucose level decrease during the second week?