We want to find the P(140 < x < 230)
To do so we find the z scores associated with both 140 and 230.
z= (x-µ)/σ
z1= (140-170)/30 = -1
z2= (230-170)/30 = 2
Applying the empirical rule, we get:
The percentage of teenage boys that have levels between 140 and 230 will be:
[tex]\text{ 34\% + 34\% + }13.5\text{\%}[/tex][tex]\text{ = }81.5\text{\%}[/tex]Therefore, the answer is 81.5%.
