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2009 AMC 10B Question 19

AMC10 · 2009 AMC 10B

Question 19

A particular $12$-hour digital clock displays the hour and minute of a day. Unfortunately, whenever it is supposed to display a $1,$ it mistakenly displays a $9.$ For example, when it is $1{:}16$ PM the clock incorrectly shows $9{:}96$ PM. What fraction of the day will the clock show the correct time?
  1. $\dfrac12$
  2. $\dfrac58$
  3. $\dfrac34$
  4. $\dfrac56$
  5. $\dfrac{9}{10}$