Nine fish are five months old. Twelve fish are seven months old. How many full months from now will the average age of the 21 fish first surpass 20 months old?
2007-01-22 11:27:08 · 7 answers · asked by Dershil P 1 in Education & Reference ➔ Trivia
Show your reasoning
2007-01-22 11:36:13 · update #1
Homework?
The answer is 14 months.
Steps: (for clarity, I've added all steps and brackets)
((9*[5+x])+(12*[7+x]))/21 = 20
((45+9x)+(84+12x))/21 = 20
(45+84+21x)/21 = 20
129+21x = 20*21
21x = 20*21-129
21x = 291
x = 291/21
x = 13.85
Rounded to nearest "month" = 14
2007-01-22 11:40:01 · answer #1 · answered by Colin M 3 · 1⤊ 0⤋
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2016-10-15 23:12:30 · answer #2 · answered by student 4 · 0⤊ 0⤋
Is it 33?
2007-01-26 10:52:15 · answer #3 · answered by shawn 1 · 0⤊ 0⤋
at 24 months?
so, from now....17 months?
2007-01-22 11:34:55 · answer #4 · answered by histruthstands 1 · 0⤊ 0⤋
8.
2007-01-26 11:47:02 · answer #5 · answered by robert m 7 · 0⤊ 0⤋
You are, of coursed, as in the meantime assuming none of them will die?
2007-01-27 09:21:00 · answer #6 · answered by marlynembrindle 5 · 0⤊ 0⤋
14months. 21fish total divided bytotalmonths is 6.3months add 14months gives20.3months
2007-01-26 05:56:09 · answer #7 · answered by ultvg 1 · 0⤊ 0⤋