4th grade math...again!

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justnkade

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4th grade math question....I need to help my son and have no clue of where to start...

He is good at math..but stumped on this one:


Use the rule 1 less than 3 times the number to make a pattern. Start with 5. What is the 4th number in the pattern?

I'm not looking for the answer..again, just a shove in the right direction...Thank you!
 
justnkade said:
4th grade math question....I need to help my son and have no clue of where to start...

He is good at math..but stumped on this one:


Use the rule 1 less than 3 times the number to make a pattern. Start with 5. What is the 4th number in the pattern?

I'm not looking for the answer..again, just a shove in the right direction...Thank you!
Click to expand...

Didn't they give you the first number of the pattern?
 
justnkade said:
I assume the first number is 5..that's what the math paper said.
Click to expand...

So the second number in the pattern would be = 3 times 5 - 1 = 3*5 -1 = 15 - 1 = 14

What would be the next (third) number?
 
That's how I started off..but didn't know if I was on the right track.

3x5 = 15-1 = 14

3x6 = 18-1 = 17

3x7 = 21-1 = 20

and

3x8= 24-1 = 23

so I guess I was on the right track?
 
justnkade said:
That's how I started off..but didn't know if I was on the right track.

3x5 -1 = 15-1 = 14

3x14 -1= 42-1 = 41

3x41 -1= 123-1 = 122

and

3x122 -1= 366-1 = 365

so I guess I was on the right track? <<< Correct - almost
Click to expand...
 
justnkade said:
Use the rule … to make a pattern.

The instruction to "make a pattern" seems vague, to me.
Click to expand...

The parent made a good pattern.

Subhotosh made another good pattern.

I could post other patterns arising from the given rule which each differ from the two patterns already posted.

I wonder what this exercise's author intends by writing "make a pattern".

 
Thank you all for your help!! It is very much appreciated.

mmm4444bot:
I quoted the question directly from the math paper that he brought home. I do agree.."make a pattern" is very vague. The math is from the book Ohio HSP Math. I think the author's intent was to totally confuse the parent!! LOL!

I will post his teacher's answer tomorrow.

Thank again to all!! Have a wonderful night!
 


Ah, well, I too suspected that Subhotosh's sequence of numbers is what the teacher expects to see, at first read.

(It's called a recursive sequence; your son will learn to work with formulas and properties for seqences of all sorts, later, in algebra.)

We can state your pattern algebraically.

Rule: 3*x - 1

Start with x = 5

x = 5 : 3*5 - 1
x = 6 : 3*6 - 1
x = 7 : 3*7 - 1
x = 8 : 3*8 - 1
x = et cetera

(This is called a linear -- or arithmetic -- sequence.)

My previous post is a sarcastic commentation on vague communication from secondary-school instructors holding expectations for parents of fourth-graders to get involved in schoolwork with their children.

If your son's teacher has no such expectations, then let me apologize to that teacher in advance.

 
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