Irene's grocery bills for two years (24 months) had a standard deviation of $15. If the lowest bill was $100 and the highest was $140, what is the range of her grocery bills?

The range is the highest value minus the lowest value. Subtract the lowest bill, $100, from the highest bill, $140: $140 − $100 = $40. The standard deviation does not affect the range, so the correct choice is $40.

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