Hello! Let’s define some variables let x= student score on the 5th test
y= increased integer value of the average
Now total of 4 students =4*78=312. Total score of 5students=312+x and average =312+x/5
New average as a result=78+y
Therefore 312+x/5=78+y —> 312+x=390+5y
x-78=5y —> x-78/5=y since y has to be an integer then x-78/5 has to be an integer and using the answer choices only (93-78)/5 is an integer so Answer is D
Hope it helps
KHow wrote:
Could someone provide an algebraic approach to this problem? I seem to be getting stuck on this. Thank you!!
-KHow
Bunuel wrote:
A student’s average (arithmetic mean) test score on four tests is 78. If each test is scored out of 100, which of the following can be the student’s score on the fifth test so that the student’s average score on the five tests increases by an integer value?
(A) 82
(B) 87
(C) 89
(D) 93
(E) 95
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