Let's calculate b; -0.5 = (1/4)(0.4) + b -0.5 =0.25(0.4) + b -0.5 - 0.1 = b -0.6 y= 0.25x - 0.6 y intercept is calculated for x=0 Then y intercepts =-0.6
<span>valid. She used a representative sample </span>because she correctly found the average and 18,000 is a reasonable number to get for a the problem