Looking for formulae

T

Tigertamer

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Jan 20, 2022
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So hopefully I'm doing this right.

I feel like I can figur out how to find the answer but I just forgot the formulae.

The first row in a section of a sports arena has 18 seats. The number of seats in each subsequent row increases by 4. If the first 130 seats of the section are reserved for secial guests, how many rows does this represend?

I tried to start with something like this:
130 = 18 + ( n + 4 ) 4
but I don't think it will give me what I want
 
1st row------18 seats
2nd row ---18+1*4 seats
3rd row----18+2*4 seats
4th row----18+3*4 seats
...
nth row----18+(n-1)*4 seats

How many seats row 1 through row n?
(18) + (18+1*4) + (18+2*4)+ (18+3*4) + ... + (18+(n-1)*4)<-----What does this sum equal (in terms of n)
What would you do next? Think inequalities!
 
Tigertamer said:
So hopefully I'm doing this right.

I feel like I can figur out how to find the answer but I just forgot the formulae.

The first row in a section of a sports arena has 18 seats. The number of seats in each subsequent row increases by 4. If the first 130 seats of the section are reserved for secial guests, how many rows does this represend?

I tried to start with something like this:
130 = 18 + ( n + 4 ) 4
but I don't think it will give me what I want
Click to expand...
You are adding MANY 18's, not just one 18!!
 
Tigertamer said:
So hopefully I'm doing this right.

I feel like I can figur out how to find the answer but I just forgot the formulae.

The first row in a section of a sports arena has 18 seats. The number of seats in each subsequent row increases by 4. If the first 130 seats of the section are reserved for secial guests, how many rows does this represend?

I tried to start with something like this:
130 = 18 + ( n + 4 ) 4
but I don't think it will give me what I want
Click to expand...
You are dealing with arithmetic progression (AP)

Have you been taught the equation for the sum of AP series knowing the first term, the common difference and the number of terms in the series.

If not, use Google for help and let us know what you find.
 
Let the OP derive those formulas.
I think that as helpers on this forum we should up our game and have students do more of their own work and stay off the internet looking for formulas.
I had a terrible tutoring session today and it has gotten me even more concerned about how math is being taught.
 
Thank you for the help. And Jomo I agree that students should do less time looking for formulas on the internet, I usealy can figure out how to things work (in math) with a bit of dificulty but I got stuck and need to use (what a programer friend of mine called) the ruber ducky methed. talk to a ruber ducky (or something of that nature) out loud and see if that makes anything come to light and if that dosen't work talk to anther human and see there opinion.
 
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