Anyone here good at doing math word problems? im stuck!

[JimB.]

Yea. If it's 17, I'm stumped.

 

[Blueeyes101817]

You really want us to post the answer to get 17?

yes please, if you dont mind..
like i was saying, i usually would just try my best then find out how to do it in class--this prof doesnt like to "teach"..she randomly picks people to go to the board and do their answer--if she picks me, i want to be able to know what im doing haha

 

[cheyita]

OK, OK, even though I usually make my DD figure stuff out on her own...

Calling them by the number of minutes:

1 & 2 go across = 2
1 comes back = 3
10 & 5 go across = 13
2 goes back = 15
1 & 2 go back across = 17

 

[Blueeyes101817]

OK, OK, even though I usually make my DD figure stuff out on her own...

Calling them by the number of minutes:

1 & 2 go across = 2
1 comes back = 3
10 & 5 go across = 13
2 goes back = 15
1 & 2 go back across = 17

mom was stumped too--i called her at work before i posted lol

THANK YOU! i didnt even think about leaving 2 there, then using them again...thanks so much!

 

[BuzznBelle'smom]

On the sequencing, is the next number 163? I think I may have the answer if it is...

 

[bopper]

Here is a good website on how to attack "next in sequence problems".
http://www.purplemath.com/modules/nextnumb.htm

 

[cheyita]

OK, for the sequence, how about 143? Anyone agree?

 

[Blueeyes101817]

thanks for the website!!

no idea about the answer...i am supposed to find 3 of the next numbers--if you have an idea about what the pattern is, please let me know...still trying to figure it out , hours later haha

 

[damo]

I've tried and tried and can't seem to find a recursive, arithmetic, geometric or exponential formula that works. I will keep trying! Do you think maybe one of the numbers is wrong? Could some of you that got answers give the formula that you think works?

 

[Blueeyes101817]

im double checking the numbers now.....The sequence is...
5, 8, 15, 31, 61, 110 ____ , _____, ______

i had a typo on the first one..that could be why no one could get it--thanks for letting me know to check!

 

[damo]

Ah!!!!! I was trying to get 100 for the 6th term! I'll try again for you!

 

[Blueeyes101817]

i completely wrote it wrong--im sorry and thanks for much for trying!!!

 

[damo]

next terms are 183, 285, 421

 

[CanBeGrumpy]

OK, here is the answer, but I'm not sure I can even explain it!! The next 3 numbers are 183, 285, and 421. Here's how it works:

First, I figured out what number added to the previous number would give the next number:

5+3=8
8+7=15
15+16=31
31+30=61
61+49=110

Next, try to find a pattern that will tell you what to add to 110 to get the next number. Hint: look at the numbers that are added to the original numbers in your sequence: 3, 7, 16, 30, 49. Try to figure out how to find the next number in THAT sequence, and you will have the next number in your original sequence. Ok, I'll post the rest because I am so afraid of forgetting what I did, but try to get it yourself first.

SPOILER AHEAD
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
..
OK, now if you look closely at the numbers we came up with to add to the original numbers (3, 7, 16, 30, 49), do you see another pattern when you do the same thing we did originally??
3+4=7
7+9=16
16+14=30
30+19=49
49+????

what are you adding each time to the number? FIVE!!
So, next you have 49+24 (because 19+5=24) =73
Add 73 to 110 to get the next number in your sequence: 183!
OK, you'll have to do the rest on your own, and I hope I didn't do a bad thing by posting the answer, but it is late and I might not remember what I did tomorrow!!!
Good luck!!!!

 

[Jessie]

In know now why I hated math

 

[damo]

Just use finite differences. You'll find that the third finite difference is 5. You can work backwards from there to determine the 9 second finite differences and the 9 first finite differences and the 9 numbers in the sequence that you need.

 

[CanBeGrumpy]

Just use finite differences. You'll find that the third finite difference is 5. You can work backwards from there to determine the 9 second finite differences and the 9 first finite differences and the 9 numbers in the sequence that you need.

Hey, how come I am an engineer and I've never heard of finite differences?? Or, maybe I heard about it 15 years ago in college, but have forgotten???

 

[damo]

It is basically what you did. When you subtract the first term from the second term or second from the third (etc) you get the first finite difference. (if these differences are constant with all the terms of the sequence then the function is linear). In this case the first finite differences are 3,7,16,30,49 and are not the same so we do the process again.


Repeat the process using the set of first finite differences. (if these second finite differences are all the same then the function is a quadratic). The second differences are 4,9,14,19 and again the second finite differences here are still different.

Then you repeat again using the second finite differences (in this case we get the third finite differences all being 5 and the same, so the function is a cubic). Now you can work your way backward to fill in the missing second and first differences and then you will get the sequence.

It is quite easy if you use a chart writing the sequence down in a column and doing the differences like a tree diagram.

 

[Blueeyes101817]

Hey, how come I am an engineer and I've never heard of finite differences?? Or, maybe I heard about it 15 years ago in college, but have forgotten???

ive never heard of that either!!
but thank you guys sooo much..you are helping so much!

 

[damo]

ive never heard of that either!!
but thank you guys sooo much..you are helping so much!

Ask your college professor if he/she used finite differences to find the solution. We teach that in tenth grade here in Ontario when we are teaching the kids how to determine if a set of points forms a linear, quadratic, or cubic function or is not a function at all.