Question

Andrea is designing the seating arrangement for a concert in her local park. To give everyone a good view, each row must have four more seats than the row before it, and the first row can only have 10 seats. Help Andrea plan the rest of the seating by solving for how many seats are in row 20. Then explain to Andrea how to create an equation to predict the number of seats in any row. Show your work, and use complete sentences.
@ganeshie8

Answer 1

too long to read

Answer 2

yes lol, however oly useful info we need to work is :-
each row must have four more seats than the row before it, and the first row can only have 10 seats.

Answer 3

first row : 10
second row : ?

Answer 4

hi @woohoo long time no see

Answer 5

@Opcode

Answer 6

yeah @ryanvarghese12790 been busy lately

Answer 7

@ryanvarghese12790 can you help pls?

Answer 8

1 sec

Answer 9

any more q?

Answer 10

@ryanvarghese12790 can you explpain cuz i didnt understand that explantion

Answer 11

@Potatoes.ramu

Answer 12

I think there are 90 seats in the 20th row..
Because here n=10(Because the first row has 10 seats)
And each row behind that has to have four more seats. So that's four seats more than the preceding row...

Answer 13

Oh oops wait. The number of seats in the 20th row is 86!

Answer 14

I thnk it is 204

cuz,

10*20+4 = 204

Answer 15

whats the formula for this arthimetic equation

Answer 16

Let s be the number of seats in the first row. So s=10.
Then there are s+4(n-1) seats in the n-th row. n is any positive integer.

Answer 17

The equation in s+4(n-1)

Answer 18

It's in series, so that's the equation :) @woohoo

Answer 19

@ryanvarghese12790 , you can't use that formula, because the number of seats keep increasing in each row.

Answer 20

so,

10+4(20-1)
14(19) = 266?

Answer 21

No what is that? Substitute n=20 in the equation I gave you to find the number of seats in the 20th row! :)

Answer 22

you all crazy i have no idea what the answer is !!!!!:D

Answer 23

so,
10+4(20-1)

Answer 24

The answer is 86! And the equation is s+4(n-1)! :P

Answer 25

@ryanvarghese12790 exactly! :P

Answer 26

that is wht I have done above

Answer 27

And you get 86! So that's the number of seats in the 20th row!

Answer 28

ok is there a name for this formula? @Potatoes.ramu

Answer 29

nope not at all

Answer 30

It's an arithmetic progression

Answer 31

how wan 14* 19 = 86

Answer 32

For instance
in this series the common difference d=4

Answer 33

@ryanvarghese12790 why are you multiplying 14 and 19. Multiply 4 and 19 and then add 10 to that.

Answer 34

ok

Answer 35

So the series goes like this. s, s+d, s+2d...... s+(n-1)d.
s+(n-1)d is the nth term.

Answer 36

s is 10 in this case. Because the first row has 10 seats. So we start with ten, And the series starts with ten.

Answer 37

@woohoo

Answer 38

wouldnt this equation work a_n=a_1+d(n-1)
@Potatoes.ramu

Answer 39

Nope.. that doesn't work! Use this one! It's definitely the right answer! Plus you get a negative sign if you subtract a and n

Answer 40

the formula is called Arithmetic formula for sequences and it is a_n=a_1(n-1)d

Answer 41

i know im ALOT late but i understand what @potatoes.ramu is saying. thanks for the help i really needed this.