65 POINTS STATISTICS
2 answers:
<h3>Answer:</h3>
- 2.25
- 2.45
In each case the expected value is the sum of products of value and its probability. (This is the definition of expected value.)
a) 1·0.3 +2·0.45 +3·0.05 +4·0.1 +5·0.1 = 2.25
b) 0·0.05 +1·0.15 +2·0.35 +3·0.25 +4·0.15 +5·0.05 = 2.45
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<em>Comment on the picture</em>
It is usually convenient to let a machine do the arithmetic, especially when the lists are long.
Here, you may notice there are only 5 contributors to the total for the second question. The first contributor for that question would be 0·0.05 = 0, so adds nothing to the total. Leaving it out makes the table sizes match, so makes the two problems easier to work with this calculator.
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