alleryStart learning →The mean of the first three of four numbers is 12 and of the last three is 15. If the last number is 28, what is the first?
A23
B17
C19
D21
Answer & Solution
Correct answer: C. 19
Subtracting the two three-number sums gives last minus first = 45 - 36 = 9, so the first is 28 - 9 = 19.
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