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Chapter 6: Q.11 (page 354)

Spell-checking Refer to Exercise 3. Calculate the mean of the random variable X and interpret this result in context.

Short Answer

Expert verified

On average there are 2.1 nonword errors in a 250-word essay.

Step by step solution

01

Given Information

The number X of nonword errors has the following distribution:

02

Explanation

The sum of each alternative multiplied by its likelihood is the expected value:

E(X)=∑xP(x)=0×0.1+1×0.2+2×0.3+3×0.3+4×0.1=2.1

This suggests that in a 250-word essay, there are on average 2.1 nonword errors.

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