Chapter 11 Data Analysis and Statistics - 11.3 Use Normal Distributions - 11.3 Exercises - Skill Practice - Page 760: 13

$97.35\%$

$|\frac{21-29}{4}|=2$, $|\frac{41-29}{4}|=3$ . The normal distribution is symmetric about the mean. Thus using the 68-95-99.7 rule and the graph we get: $P(\overline{x}-2\sigma\leq x\leq\overline{x}+3\sigma)=34\%+13.5\%+34\%+13.5\%+2.35\%=97.35\%$