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70% of Ms. Miller's class passed the test on the first try. Those who failed were able to retake and half of those students passed on their second try. If there are 20 students in the class, what overall percentage passed the test?

 Oct 13, 2021
 #1
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70% passed the test: (\(\frac{20}{100}*70\)) is 14.0,

so 14 students passed at the first try. (20 students)

 

30% failed the test: (\(\frac{20}{100}*30\)) is 6.0,

so 6 students failed at the first try. (20 students)

 

The half of 30% is (\(30:2=\)) 15%.

Imagine if the 30% would be 100%, means all students failed, 

and at total they're only 6 students, so wouldn't it be 15%,

but it would be the half of 100%, so: (\(100:2=\)) 50%.

6 students are 100% and 50% would be (\(6:2=\)) 3 students.

At the second try 3 students will pass and the other 3 stud. will fail.

 Oct 13, 2021
 #2
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first try: 0.70 * 20 = 14 passed , 6 failed
second try: 0.5 * 6 = 3 passed
so 14 + 3 = 17 out of 20 passed
100(17/20) = 5*17 = 85%

 Oct 13, 2021

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