Homework Help Forum: Algebra 1

Posted by Zach on Thursday, November 5, 2009 at 11:04pm.

Mary's class took two tests last week. 80% of the class passed the math test, 90% of the class passed the English test, and 72% of the class passed both. What is the probablility that a randomly selected student in Mary's class failed both tests? Express your answer as a percent rounded to the nearest tenth of a percent? Thanks -Zach

• Algebra 1 - Reiny, Thursday, November 5, 2009 at 11:11pm

  Prob(Math OR English) = P(M) + P(E) - P(M and E) = .8 + .9 - .72 = .98 Prob (failing both) = 1 - .98 = .02

  
  

• Algebra 1 - Zach, Thursday, November 5, 2009 at 11:26pm

  Thanks

  
  

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