Question

Your friend is trying to grow her hair as long as her cousin’s hair. The table shows their hair lengths y (in inches) in different months x. Month Friends Hair(in) Cousins Hair(in) 3 4 7 8 6.5 9. solve for the cousins hair.

Answer 1

Given the table that shows the hair lengths y (in inches) of your friend and her cousin in different months x.

Month      Friends Hair(in)      Cousins Hair(in)
    3                     4                              7
    8                    6.5                            9.

To solve for the cousins hair, recall that the equation of a line is given by

y = mx + c

From the table,

7 = 3m + c . . . (1)
9 = 8m + c . . . (2)

(1) - (2) ⇒ -2 = -5m
$\Rightarrow m= \frac{2}{5} =0.4$

Substituting for m into equation (1) gives:

$7=3(0.4)+c \\ \\ \Rightarrow c=7-1.2=5.8$

Therefore, the equation representing the growth of the cousin's hair is given by y = 1.2x + 5.8