Abby scored a 78 on her first test and a 54 on her second. If Abby needs a test average of 55 to pass the course, what is the lowest score that she can make on her third and final test and still pass?

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Answer 1 · 2016-11-08T08:29:24

#55#

The lowest average of the 3 tests must be 55 in order for Abby to pass.

Let the lowest mark be #m#

#(78+54+m)/3 = 55" "larr xx 3#

#78+54+m = 165#

#m = 165-78-54#

#m = 33#

The high mark in the first test means that she only needs 33 in the third test to have an average of #55#.