There are 7 positive examples and 4 negative ones overall, so the overall entropy is –(7/11)×log2(7/11) – (4/11)×log2(4/11) which is about 0.94566.

In the exam, you will not have a calculator. You will not, of course, be expected to work out the logarithms by hand. :-) You should therefore leave the entropy as an unevaluated expression: –(7/11)×log2(7/11) – (4/11)×log2(4/11).)

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