Slide 9: Numerically Summarizing Data

ph in Water: The acidity or alkalinity of a solution is measured using pH. A pH less than 7 is acidic; a pH greater than 7 is alkaline. The following data represent the pH in samples of bottled water and tap water.

Tap

7.64

7.45

7.47

7.50

7.68

7.45

7.10

7.56

7.47

7.52

Bottled

5.15

5.09

5.26

5.20

5.02

5.28

5.26

5.13

5.26

5.21

7.69

7.47

5.23

5.24

(a) Determine the mean, median, and mode pH for each type of

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water. Comment on the differences between the two water types.

(b) Suppose the pH of 7.10 in tap water was incorrectly recorded as 1.70. How does this affect the mean? the median?