Question

a chef knows that ground beef used for hamburger is safe to eat once it reaches 160 degrees fahrenheit. for optimized taste and safety, he will not allow a hamburger cooked to a temperature under 160 degrees or over 170 degrees to be served. which graph represents the conditions under which the chef will not allow the hamburger to be served? 156 160 164 168 172 156 160 164 168 172 156 160 164 168 172 156 160 164 168 172

Explanation:

Step1: Define forbidden temperatures

Let $T$ = hamburger temperature. Forbidden: $T < 160$ or $T > 170$.

Step2: Match to number line rules

Open circles for $<$/$>$ (exclude 160, 170); shade left of 160, right of 170.

Step3: Identify correct graph

First graph has open circles at 160,172 (170 equivalent here), shaded outside.

Answer:

The first option: $\boldsymbol{\longleftarrow\hspace{1em}\text{---}\hspace{0.2em}\circ\hspace{0.2em}\text{----}\hspace{0.2em}\circ\hspace{0.2em}\text{---}\hspace{1em}\longrightarrow}$ (with open circles at 160 and 172, shading to the left of 160 and right of 172)