25,30,35,40,45.

mean = 25+45/2=70/2=35

\(\sigma^2 = \frac{(25-35)^2+(30-35)^2+(35-35)^2+(40-35)^2+(45-35)^2}{5}\)

\(\sigma^2 = \frac{100+25+0+25+100}{5}\)

\(\sigma^2 = \frac{250}{5}\)

\(\sigma^2 = 50\)

\(\sigma = \sqrt{50} \approx 7\)

where \(\sigma\) is standard deviation.

How many integers in the dataset are within 1 std dev about the mean=35

Minimum= 35-7=28

Maximum= 35+7=42

Ans: 3 (30, 35 and 40)

_________________

~fluke

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