IELTS® Academic Reading Practice 81

The answer is D. Paragraph D explains the factors affecting the transmission of information. It discusses how 'noise sets a limit on the rate at which information can pass along communication channels while remaining error-free,' and how this rate 'depends on the relative strengths of the signal and noise travelling down the communication channel, and on its capacity (its “bandwidth”).' These details describe what affects the transfer or transmission of information.

Associated Text:
“Noise usually means unwanted sounds which interfere with genuine information. Information theory generalises this idea via theorems that capture the effects of noise with mathematical precision. In particular, Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free. This rate depends on the relative strengths of the signal and noise travelling down the communication channel, and on its capacity (its 'bandwidth').”

The answer is F. Paragraph F gives an example of how unnecessary information can be omitted. It describes how Shannon worked on 'stripping out superfluous (“redundant”) bits from data which contributed little real information.' It also mentions, 'As mobile phone text messages like “I CN C U” show, it is often possible to leave out a lot of data without losing much meaning.' These are clear examples of omitting unnecessary information.

Associated Text:
“Shannon also laid the foundations of more efficient ways of storing information, by stripping out superfluous ('redundant') bits from data which contributed little real information. As mobile phone text messages like 'I CN C U' show, it is often possible to leave out a lot of data without losing much meaning.”

The answer is B. Paragraph B contains a reference to Shannon's attitude to fame. It specifically states that, although Shannon 'developed information theory,' he 'shunned the resulting acclaim.' This sentence directly addresses his reaction to the recognition he received for his work, which is an attitude to fame.

Associated Text:
“While at Bell Laboratories, Shannon developed information theory, but shunned the resulting acclaim.”

The answer is E. Paragraph E provides details of a machine capable of interpreting incomplete information. It mentions the 'Universal Product Code, or bar code, which uses a simple error-detecting system that ensures supermarket check-out lasers can read the price even on, say, a crumpled bag of crisps.' This example describes how a machine can interpret data even if it is not fully complete or perfectly presented.

Associated Text:
“Other codes have become part of everyday life - such as the Universal Product Code, or bar code, which uses a simple error-detecting system that ensures supermarket check-out lasers can read the price even on, say, a crumpled bag of crisps.”

The answer is A. Paragraph A presents a detailed account of an incident involving information theory. It describes the 2002 event where NASA sent a message to Voyager I using techniques from information theory, resulting in a successful remote repair. The paragraph explains the context, problem, and the outcome, thus fulfilling the requirement for a detailed account.

Associated Text:
“In April 2002 an event took place which demonstrated one of the many applications of information theory. The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars. After 25 years of exposure to the freezing temperatures of deep space, the probe was beginning to show its age. Sensors and circuits were on the brink of failing and NASA experts realised that they had to do something or lose contact with their probe forever. The solution was to get a message to Voyager I to instruct it to use spares to change the failing parts. With the probe 12 billion kilometres from Earth, this was not an easy task. By means of a radio dish belonging to NASA's Deep Space Network, the message was sent out into the depths of space. Even travelling at the speed of light, it took over 11 hours to reach its target, far beyond the orbit of Pluto. Yet, incredibly, the little probe managed to hear the faint call from its home planet, and successfully made the switchover.”

The answer is C. Paragraph C refers to what Shannon initially intended to achieve in his research by stating that 'he set out with an apparently simple aim: to pin down the precise meaning of the concept of “information”.' It also says 'the down-to-earth uses Shannon originally had for his work,' making clear his original intention for the research.

Associated Text:
“This all seems light years away from the down-to-earth uses Shannon originally had for his work, which began when he was a 22-year-old graduate engineering student at the prestigious Massachusetts Institute of Technology in 1939. He set out with an apparently simple aim: to pin down the precise meaning of the concept of 'information'.”