ANSWER:
B. 2 4/7 hr
STEP-BY-STEP EXPLANATION:
We have the following:
Rate Wiilie = 200 words in 6 hours
Rate Myra = 200 words in 4 1/2 hours
Together then it would be 200 words in x hours.
We can formulate the following equation:
[tex]\frac{200}{x}=\frac{200}{6}+\frac{200}{4\frac{1}{2}}[/tex]
We solve for x:
[tex]\begin{gathered} \frac{1}{x}=\frac{1}{6}+\frac{1}{4\frac{1}{2}} \\ \\ \frac{1}{x}=\frac{1}{6}+\frac{1}{\frac{9}{2}} \\ \\ \frac{1}{x}=\frac{1}{6}+\frac{2}{9} \\ \\ \frac{1}{x}=\frac{1*9+2*6}{6*9}=\frac{9+12}{54}=\frac{21}{54}=\frac{7}{18} \\ \\ x=\frac{18}{7}=2\frac{4}{7}\text{ hours} \end{gathered}[/tex]
So the correct answer is B. 2 4/7 hr
