nitindewan Posted February 21, 2003 Share Posted February 21, 2003 Hi, Encountered this as a problem in one of the tests i was doing in princeton review : If you are asked to round off - say 2.446 to 1 decimal places is the answer simply 2.4 or is the answer 2.5 - as a result of "cumulative rounding" - i.e. round off 2.446 to 2.45 and then to 2.5 .... The actual DS question used a square and a triangle in place of two digits and we were required to find out the digits. What are therefore the rounding off rules followed by the folks at ETS ? Quote Link to comment Share on other sites More sharing options...
valterduarte Posted March 28, 2003 Share Posted March 28, 2003 Hi there! 2.5 You can never do "cumulative rounding" since that would be error propagation. Quote Link to comment Share on other sites More sharing options...
bombomba Posted March 29, 2003 Share Posted March 29, 2003 Originally posted by valterduarte Hi there! 2.5 You can never do "cumulative rounding" since that would be error propagation. I agree you can't do cumulative rounding. The answer, therefore, should be 2.4 2.446 -> round down to 2.4 Quote Link to comment Share on other sites More sharing options...
raghuveer_v Posted March 29, 2003 Share Posted March 29, 2003 In my opinion, rounding-off should result in the best approximation (least error) to the actual value. for example, if you round off 2.446 to 1 decimal digit by "truncating", we have 2.4, the magnitude of the error being | 2.446 - 2.4 |= 0.046 on the other hand, if you round off using "cumulative rounding", we have 2.5, the magnitude of error being | 2.446 - 2.5 | = 0.054 So, I'd say the first one is correct. But that doesn't mean that "truncating" is always the better choice. This problem arises when you round x.x...4x to x.x...5. If you have the time, plotting the numbers on a number line would be a good way: 2.4 2.5 x x | | | | | | | | | | | | | |.........|.........|.........|.........|.........|.........|.........|.........|.........|.........|.........|.........| ^ ^ 2.446 2.45 you can clearly see which is the better approximation. Quote Link to comment Share on other sites More sharing options...
sushilksood Posted April 30, 2003 Share Posted April 30, 2003 What is the answer finally? Quote Link to comment Share on other sites More sharing options...
dgajaria Posted May 2, 2003 Share Posted May 2, 2003 2.4 Quote Link to comment Share on other sites More sharing options...
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