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Camellia took her geography test. She scored 100 on her exam which was found to raise the class average on the test
from 74 to 76. ( before adding her school the average was 74 ) how many students including Camelia took the test?
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Let n = "how many students including Camelia took the test".
Since the average score was 74 for (n-1) students (before Camelia took the test)
the total scores were 74*(n-1) at that time.
Camelia contributed 100 scores to the total, so now the average is
76 = .
From this equation
76n = 74*(n-1) + 100, or
76n = 74n - 74 + 100,
which gives
76n - 74n = 26
2n = 26
n = 26/2 = 13.
ANSWER. 13 students, including Camelia.
Solved.
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