Often, frequency distributions are reported using unequal class widths because the frequencies of some groups would otherwise be small or very large. Consider the following data, which represent the daytime household temperature the thermostat is set to when someone is home for a random sample of 750 households.

A- Determine the class midpoint, if necessary, for each class and approximate the mean and standard deviation temperature

Temp (F) Frequency.

61-64 31

65-67 67

68-69 198

70 195

71-72 120

73-76 89

77-80 50

The frequency distribution on the following represent the age of people living in proverty in 2009 (in thousands). In this frequency distribution, the class widths are not the same for each class. Approximate the mean and standard deviation age of a person living in poverty. For the open ended class of 65 and older, use 70 as the class midpoint.

Age Frequency

0-17 15,451

18-24 6071

25-34 6123

35-44 4756

45-54 4421

55-59 1792

60-64 1520

65 and older 3433