Exercises 25 1.24. The utilities data set contains information from utilities bills for a personal residence over a number of years. The variables gasbill and ccf contain the gas bill (in dollars) and usage (in 100 cubic feet) for a personal residence. Use plots to explore the cost of gas over the time period covered in the utilities data set. Look for both seasonal variation in price and any trends over time. 1.25. The births78 data set contains the number of births in the United States for each day of 1978. a) Make a histogram of the number of births. You may be surprised by the shape of the distribution. (Make a stemplot too if you like.) b) Now make a scatterplot of births vs. day of the year. What do you notice? Can you conjecture any reasons for this? c) Can you make a plot that will help you see if your conjecture seems correct? (Hint: Use groups.)

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