The combined age of a fox and hen is 91yrs old. The Fox is currently twice the age the hen was when the fox was the same age as the hen is now!How old is the fox?
2006-09-09 07:47:45 · 32 answers · asked by Mac 2 in Science & Mathematics ➔ Mathematics
Fox: age now, F. Hen's age now, H. F+H=91. F = 2(H-z) F-z=H. Combine last two eqns: F = 2(F-z-z), or F=4z. Use first and third equations: F+F-z=91, or 2F-z = 91, or 8z - z = 91, or 7z = 91, or z = 13. Hence F = 52, and H = 39. Checking, 13 years ago, the fox was 39 and the hen was 26.
2006-09-09 08:00:24 · answer #1 · answered by Anonymous · 2⤊ 0⤋
Fox: age now, F. Hen's age now, H. F+H=91. F = 2(H-z) F-z=H. Combine last two eqns: F = 2(F-z-z), or F=4z. Use first and third equations: F+F-z=91, or 2F-z = 91, or 8z - z = 91, or 7z = 91, or z = 13. Hence F = 52, and H = 39. Checking, 13 years ago, the fox was 39 and the hen was 26.
2006-09-10 04:35:11 · answer #2 · answered by green_maths_scout 2 · 0⤊ 0⤋
Got it in about three, using a less mathematically safe method - I looked for a high factor in 91. 13 seemed a good bet so I played around with multiples of 13 until I got the fabled "fox is 52, hen is 39" answer.
2006-09-10 11:20:36 · answer #3 · answered by chris_ninety1 5 · 0⤊ 0⤋
Hen 39 fox 52
difference 13
52 = 2x(39-13)
3 min
2006-09-09 08:28:31 · answer #4 · answered by debarun p 1 · 0⤊ 0⤋
age of fox x
age of hen = y
x+y = 91
when fox was y year hen was y-(x-y) = 2y -x
x = 2(2y-x)
= 2(2(91-x) -x)
= 2(182-3x)
so 7x = 364
x = 52
y = 39
so fox is 52 years solved in 3 minutes. But hen does not live 39 years so question is wrong
2006-09-09 18:06:21 · answer #5 · answered by Mein Hoon Na 7 · 0⤊ 0⤋
neither hens nor foxes live to be more than 15 years of age, there it only took me 1 minute!
2006-09-11 02:05:35 · answer #6 · answered by � Fuzzy Dice 5 · 0⤊ 0⤋
Not in 5 minutes but did eventually, its amazing how many people didn't read the question. The fox is 52.
2006-09-10 10:34:29 · answer #7 · answered by John B 2 · 0⤊ 0⤋
The fox is 61 years old
2006-09-09 08:08:51 · answer #8 · answered by LEONEL_VR 1 · 0⤊ 0⤋
i think so
fox age = 2 * hens age
hens age = x
3x = 91
so x = 30.3333...
therefore fox = 60.6666.... years old
that took 3 mins including typing
2006-09-09 08:04:01 · answer #9 · answered by narglar 2 · 0⤊ 0⤋
sod it let the fox eat the hen it'll take less than 5 minutes
2006-09-09 07:55:00 · answer #10 · answered by peter.w 4 · 0⤊ 0⤋