Fiona recorded the mean math exam grade for six random samples of students from the entire seventh-grade class. Sample Sample Mean Grade165292378445595670Why is a valid prediction for the mean of the population not possible using these samples?

The six sample mean grades range from 65 to 95, a spread of 30 points. That large variation means the sample means do not give a consistent estimate of the population mean, so Fiona cannot make a reliable prediction from them. The correct choice is “The variation of Fiona’s samples is too large.”

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