# Computing sample standard deviations

1. Compute the sample standard deviation of the data set 6,4,2,1,4,1

2. A test has 6 multiple choice questions, each with 4 alternatives. What is the probability of guessing 5 or more questions correctly?

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#### Solution Preview

1.The mean of the series is m = 3

variance = 1/n * ∑ (x-m)^2 = 3

then standard deviation = SQRT(variance) = SQRT(3) = 1.73

2. In this case, the probability of guessing one correct is 1/4 = 0.25

The binomial ...

#### Solution Summary

The solution provides brief, clear explanations of how to compute a sample standard deviation of a data set. The expert also answers a question regarding the probability of guessing answers to a test. An Excel document is provided.

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