Beyond Common Core
Problem 26 of 45s12-026
A carnival game pays dollars: $0 with probability 0.3, $5 with probability 0.6, and $10 with probability 0.1. What is the standard deviation of ?
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Solution walkthrough1:50
- SD is a typical distance from the mean: square each deviation, weight it by its probability, add, take the root.
- Mean: dollars.
- Deviations from : , and . Squared, they are , and .
- Weight and add: .
- The variance is in square dollars, so take the root: dollars.
- Traps: is the variance, squares not , and never squares the distances.