Question

Select the exit door with the correct answer to the problem etched into the stone.

• A. Door B: 5.682
• B. Door D: 110
  
• C. Door C: 220
• D. Door A: 440

Answer 1

The correct option is A Door B: 5.682

$Thegivenproblemis:5^2\times [{(7^{-1}-{77}^{-1})}^{-1}-{(3^{-1}-{33}^{-1})}^{-1}{]}^{-1}Solvethebracketsfirst:=5^2\times [{(\frac{1}{7}-\frac{1}{77})}^{-1}-{(\frac{1}{3}-\frac{1}{33})}^{-1}{]}^{-1}=5^2\times {[{\left(\frac{10}{77}\right)}^{-1}-{\left(\frac{10}{33}\right)}^{-1}]}^{-1}=5^2\times {\left[\right(\frac{77}{10})-(\frac{33}{10}\left)\right]}^{-1}=5^2\times {\left[\right(\frac{44}{10}\left)\right]}^{-1}=25\times \frac{10}{44}\approx 5.68$
Option b will be the answer.