SOLUTION: 1/4 of this seniors have averages above 90. 1/2 of the remainders have averages between 80 and 90. what part of the senior class have averages below 80?

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Question 387998: 1/4 of this seniors have averages above 90. 1/2 of the remainders have averages between 80 and 90. what part of the senior class have averages below 80?
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
1/4 of the seniors have averages above 90.
The remainder is 3/4 of the seniors.
1/2 of the remainders have averages between 80 and 90.
That means that 1/2 * 3/4 of the seniors have averages between 80 and 90.
That means that 3/8 of the seniors have averages between 80 and 90.
The total number of seniors that have averages above 80 is equal to 1/4 + 3/8.
Since 1/4 = 2/8, then the total number of seniors that have averages above 80 is equal to 5/8.
That leaves 3/8 of the seniors that have averages below 80 because 5/8 + 3/8 = 8/8 = 1.