More Math Questions =D

etalns

Diamond Member
Dec 20, 2001
6,513
1
0
Hey all, just going over some work and these are some questionsI 'm getting that I've gotten wrong. Looking back on them and still can't figure out what I'm doing wrong on some of them.

The first question deals with geometric sequences. Always had trouble with this for some reason =(

I will add questions as they come up, thanks all for your help over the last few days, it really is appreciated. I have my exam tommorow :(



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1) Determine the indicated term of the geomtric sequence.

a) 1,2,4,...t6

Answer:

Use tn=ar^(n-1)

a = 1
r = 2
n-1 = 5

tn=1(2)^5 = 32
t6 = 32



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2) Prezwalski's wild horse is the only known species of wild horse left in the world. In 1956, there was only 36 of them. They were taken into protective captivity and there was an international effort towards registered breeding. By 1976, there were 250 wild horses. Copy and complete the table. Assume the populations are terms of a geomtric sequence.

Year - Population

1956-36
1961- ?
1966- ?
1971- ?
1976- 250
1981- ?
1986- ?
1991- ?
1996- ?

Answer:
t5 = 36 * r ^(n-1)
t5 = 36 * r^(4) = 250
r^(4) = 250/36
r=(250/36)^(1/4)
r= 1.62333958

so

1956 - t1 = 36
1961 - t2 = 58
1966 - t3 = 95
1971 - t4 = 154
1976 - t5 = 250
1981 - t6 = 406
1986 - t7 = 659
1991 - t8 = 1069
1996 - t9 = 1736


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Let *root* represent your square root sign, let ^# (replace # with value) represent your exponents
 

bmd

Golden Member
Feb 17, 2001
1,043
0
0
looks like you solved #1...

For number 2...

t5 = 36 * r ^(n-1)
t5 = 36 * r^(4) = 250
r^(4) = 250/36
r=(250/36)^(1/4)
r= 1.62333958

so

1956 - t1 = 36
1961 - t2 = 58
1966 - t3 = 95
1971 - t4 = 154
1976 - t5 = 250
1981 - t6 = 406
1986 - t7 = 659
1991 - t8 = 1069
1996 - t9 = 1736

Feel free to rip me a new one if I am wrong :p.

Edit: You also have 1966 and 1986 listed twice in your list of years, that might have messed you up.
 

etalns

Diamond Member
Dec 20, 2001
6,513
1
0
Yours appears to be right. Let me find another q and apply the formula and see what I come up with.
 

bmd

Golden Member
Feb 17, 2001
1,043
0
0
Post more Qs if you want, kinda bored and need to do some of this kinda stuff before I go back to school to practice my rusty math skills :p.
 

etalns

Diamond Member
Dec 20, 2001
6,513
1
0
Originally posted by: bmd
looks like you solved #1...

For number 2...

t5 = 36 * r ^(n-1)
t5 = 36 * r^(4) = 250
r^(4) = 250/36
r=(250/36)^(1/4)
r= 1.62333958

so

1956 - t1 = 36
1961 - t2 = 58
1966 - t3 = 95
1971 - t4 = 154
1976 - t5 = 250
1981 - t6 = 406
1986 - t7 = 659
1991 - t8 = 1069
1996 - t9 = 1736

Feel free to rip me a new one if I am wrong :p.

Edit: You also have 1966 and 1986 listed twice in your list of years, that might have messed you up.

That's right =)

Good job! and thanks so much!

 

eakers

Lifer
Aug 14, 2000
12,169
2
0
i recommend getting together with other people in your class

math is a social subject.

thats why i love it.
 

bmd

Golden Member
Feb 17, 2001
1,043
0
0
Talking w/ Qosis in AIM now, easier than posting back and forth :p.