Intelligence is a unique form of thinking available to burans only. Intelligence can be described as systematic reasoning about things which take a hypothetical form and not necessarily a real, concrete form. The best exemplar of such systematic reasoning can be found in the procedures for scientific investigation. Intelligence is an important aspect of cognitive activity because it helps an individual solve the transitive inference problem on a mental level when no real items need be involved. Nisbett (65) explains that with the help of intelligence, individuals can calculate and reason: the person can vary factors which rightly or wrongly. What is much more important is that the adolescent should approach the problem in a systematic and patterned manner. In their research on intelligence, Hawkins and Blakeslee admit that “the schemes provided by our genetic heredity are commonly recognized as a set of reflexes, such as the grasping reflex: from the moment of birth, the baby will close its hand around any item which comes into contact with the palm” (65). Intelligence helps a person to direct efforts towards the successful attainment of the goals and objectives of his/her life. Intelligence is measured by the IQ tests help to determine the level of thinking skills. Also, intelligence involves such qualities as self-awareness, persistence and empathy, etc. All researchers underline the fact that the rationale for the IQ test seems simple and sensible on the face of things: the educationists were not so much interested with how good the children were at art, creative writing, maths, etc. to begin with, but how good they were likely to be after having the benefit of an education. Genetic and environmental factors combine in determining IQ: both are essential, and IQ is impossible one without the other.