解:
(1)如圖所示
(2)設(shè)$y = ax + b,$把$(23,156),$$(24,163)$代入得:
$\begin{cases}23a + b = 156\\24a + b = 163\end{cases}$
用$24a + b = 163$減去$23a + b = 156$得:
$24a + b-(23a + b)=163 - 156,$
$24a + b - 23a - b = 7,$
$a = 7。$
把$a = 7$代入$23a + b = 156$得:
$23\times7 + b = 156,$
$161 + b = 156,$
$b=-5。$
所以$y = 7x - 5。$
(3)當(dāng)$x = 25.8$時(shí),$y = 7\times25.8-5=180.6 - 5 = 175.6。$
所以估計(jì)這個(gè)人的身高為$175.6cm。$