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Exercise 43

Avg difficulty 3.0

Cost of breakfast. Sally gets a cup of coffee and a muffin every day for breakfast from one of the many coffee shops in her neighborhood. She picks a coffee shop each morning at random and independently of previous days. The average price of a cup of coffee is $1.40 with a standard deviation of 30¢ ($0.30), the average price of a muffin is $2.50 with a standard deviation of 15¢, and the two prices are independent of each other.

  1. What is the mean and standard deviation of the amount she spends on breakfast daily?

  2. What is the mean and standard deviation of the amount she spends on breakfast weekly (7 days)?

Diez, Barr & Çetinkaya-Rundel, OpenIntro Statistics, Probability, End-of-Chapter Exercises, Exercise 43

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Adapted from OpenIntro Statistics © 2019 David Diez, Mine Çetinkaya-Rundel & Christopher D. Barr. Licensed under CC BY-SA 3.0. Source: OpenIntro Statistics. Imported at revision fee2509.