o keep the spectators out of the line of flight at an air show, the ushers arranged the show's seats in the shape of an inverted triangle. Kevin, who loves airplanes, arrived very early and was seated in the front row, which contained one seat. The second row contained three seats, and those filled very quickly. The third row contained five seats, which were given to the next five people who came. The next row contained seven seats. This seating pattern continued all the way to the last row, with each row containing two more seats than the previous row. All 20 rows were filled. How many people attended the air sh

Answers

Answer 1

Answer:

400 people attended the air show.

Step-by-step explanation:

Arithmetic sequence:

An arithmetic sequence has the following general equation:

[tex]a_n = a_1 + d(n-1)[/tex]

In which [tex]a_n[/tex] is the nth term, [tex]a_1[/tex] is the first term and d is the common difference between the terms.

The sum of the first n terms of an arithmetic sequence is given by:

[tex]S_n = \frac{n(a_1+a_n)}{2}[/tex]

In this question:

First row 1 seat, second 3 seats, 3rd 5 seats and so on.

So we have the following arithmetic sequence:

{1,3,5,7,9,...}

So [tex]a_1 = 1, d = 9 - 7 = 7 - 5 = ... = 2[/tex]

So

[tex]a_n = 1 + 2(n-1)[/tex]

All 20 rows were filled. How many people attended the air show?

Sum of the 20 terms of the progression. So

[tex]S_{20} = \frac{20(1+a_{20})}{2} = 10(1+a_{20})[/tex]

The 20th term is:

[tex]a_{20} = 1 + 2(20-1) = 1 + 2*19 = 1 + 38 = 39[/tex]

So

[tex]S_{20} = 10(1+a_{20}) = 10(1 + 39) = 10(40) = 400[/tex]

400 people attended the air show.


Related Questions

Find the other endpoint when the midpoint is (4, 1) and one endpoint is (5,-1)​

Answers

Answer:

(3,3)

Step-by-step explanation:

the difference between 5 and 4 is 1 so move down 1 from the mid point giving you 3

the difference between 1 and -1 is 2 so move right 2 from the mid point giving you 3

(3,3)

Answer pls thank you

Answers

Answer:

I got 5.19.

Step-by-step explanation:

With this number there is no way to get a perfect sqaure. When you square root it, you get a decimal. If there's an option where it says no perfect square I'd suggest putting that

What's the perimeter?

Answers

Answer: D. 56 Units?

Explanation:
Side 1 - 9
Side 2 - 4
Side 3 - 4
Side 4 - 8
Side 5 - 11
Side 6 - 3
Side 7 - 2
Side 8 - 15

Added together: 56

Answer:

The perimeter would be 55 units

Determine the amount or number of something mathematically

Answers

2.586 is the answer cause you said mathematically

how do I add this? 1 3/4 + 3 2/8

Answers

Answer:

5

Step-by-step explanation:

Answer:

The answer would be 5

Step-by-step explanation:

Which is greater 27 or 72

Answers

Answer:

72??? For greater wise? Then yeah, 72.

Step-by-step explanation:

Answer:

there both equal if you add 2 and 7 equals 9

if you had 7 and 2 equals 9

Step-by-step explanation:

-2y + 4 > 10

solve the inequality

Answers

Step-by-step explanation:

-2y+4>10

subtract 4 from both sides

-2y+4-4>10-4

-2y>6

divide both sides by two

-2/2y>6/2

-1y>3

if negative y is greater than three than you have to multiply both sides of the equation by -1

y>-3 if you put that back into the earlier equation it is impossible.

so we have to switch the signs to < or less than

y<-3

Hope that helps:)

Simplify the expression 10 + 2(n + 5) + 4n

Answers

Answer:

6n + 20

Step-by-step explanation:

10 + 2n + 10 +4n

6n +20

Answer:

[tex]10 + 2n + 10 + 4n \\ 6n + 20 \\ 2(3n + 10)[/tex]

What is the y intercept of a line that passes through the points (2, -2.5) and (4, -2)

Answers

Answer:

-3

Step-by-step explanation:

To find the slope of this line, you have to subtract that first y coordinate from the second y coordinate, and divide that by the quantity equal to the second x coordinate minus the first.

-2 - -2.5 = 0.5

4 - 2 = 2

0.5/2 = 1/4

Now you plug in the info you already have into a y=mx+b format. Chose one of the pairs of coordinates given in instruction to be the x and y values.

-2 = 1/4(4) + b

-2 = 1 + b

-3 = b

-3 is the y-intercept.

If you buy 4 turkey subs that in total costs 26 dollars how much would 5 turkey subs cost.

Answers

Answer:

33/32.5

Step-by-step explanation:

26 divided by 4 equals 6.5

then 6.5 times 5 equals 32.5

Please I need some help hereeeeeeeeee

Answers

ANSWER- volume

The shaded cube has a volume of 1 cubic unit. Cubes like this one will be used to completely fill a rectangular prism that has the dimensions shown. How many of these shaded cubes will be needed to completely fill the rectangular prism? What you are trying to find?

Answer and explain I’ll mark brainliest please help!!!!!

Answers

Answer:

230 were sold at the door

170 were sold in advance

Step-by-step explanation:

x=at door y=in advance

x+y=400

3x+2y=1030

y=-x+400

2y=-3x+1030

y=-3/2x+515

-x+400=-3/2x+515

x=230 y=170

PLEASE HELP !!

Find the lateral area of this cone. Leave your answer in terms of pi.

25 cm

8 cm

Answers

Answer:

200

Step-by-step explanation:

pi · radius · height

3.14 · 8 · 25 = 200

extra : i used symbolab.com :)

can somebody help me?

Answers

The answer is 8 ( a + 2c)


1,2,3 or 4?

Look at the picture.
Thank u!

Answers

Answer:

option 2

4/7

Step-by-step explanation:

Multiply 4/3x3/7 = 12/21

now simplify  12/21 = 4/7

PLEASE HELP URGENT!!
WILL GIVE BRAINLIEST

find the area of the composite figure.
-126 cm2
-140 cm2
-252 cm2
-280 cm2

Answers

Answer:

252cm².

because,

we know Formula for finding Area of Trapizm.

That is,

1/2 × Sum of length of parallel sides × Height.

Here, we have 2 congruent Trapizm.

so,

Lengths of parallel sides = 16 and 20.

16 + 20 = 36.

Height = 7 cm.

Using Formula.

1/2 × 36 × 7

18 × 7

126 cm²

Here, we have two Trapizm...

so that..

126 × 2 = 252cm².

Answer:

252cm².

Step-by-step explanation:

I took the test

It costs $40 to register for Karate, then $15 per lesson. If Rachel is taking lessons and wants to spend no more than $250, how many lessons can she take?​

Answers

Answer:

14 lessons.

Step-by-step explanation:

Hahahhahahahahahahahahhahahahahah
25

The inner circle circumference is 52 ft. the distance between the inner and the outer circle is 8ft. By how many ft is the outer circle larger?

Answers

Answer:

The outer circle is 16 feet larger than the inner circle (68 - 52).

Step-by-step explanation:

Given that the inner circle circumference is 52 feet, and the distance between the inner and the outer circle is 8 feet, to determine by how many ft is the larger outer circle, the following calculation must be performed:

The radius of a circle is equal to half its diameter. Therefore, the radius of the inner circle is 26 feet. Thus, if the distance between the two circles is 8 feet, the radius of the outer circle is 34 feet (26 + 8). Therefore, the diameter of this circle is 68 feet (34 x 2).

This implies that the outer circle is 16 feet larger than the inner circle (68 - 52).

Select the Ratio that is not equivalent to the rest.
25 points
12:25
6:15
14:35
2:5

Answers

12:25 is not equivalent to the rest

In ΔMNO, m = 55 inches, n = 48 inches and o=59 inches. Find the measure of ∠O to the nearest 10th of a degree.

Answers

Answer: 69.5 degree

Can someone please help me what's the answer?

Answers

Answer:

k=77

Step-by-step explanation:

put this as the equation k/11=7

what divided by 11 equals 7. Just multiply 11 and 7 to get the answer.

y=3x-4 slope intercept form

Answers

Answer:the slope is 3 and the y intercept is -4

Step-by-step explanation:

The receipt below shows the money, in dollars, spent by a customer at the good groceries stores

Answers

C. Good groceries charges 1.20 dollars per kilogram of lettuce. Hope this helps!!

1.) Eight monkeys eat 16 lb of bananas a day. How many pounds of bananas are needed to feed 10 monkeys?​

Answers

Answer:

20, since it has a rate of 2 banana per monkey so for 10 monkeys there will be 20, as the rate 1/2X x= monkeys

Step-by-step explanation:

find the square root of 14+6√5​

Answers

Answer:

3 + √5

Step-by-step explanation:

Find the square root of 14+6√5​

Change to √ ( 14 + 6√5 ) = √x + √y

1️⃣ Square.

14 + 6√5 = x + y + 2√xy

14 + 2√45 = ( x + y) + 2√xy

2️⃣ Compare.

(x + y) = 14

xy = 45

3️⃣ Solve.

(x - y)² = (x+y)² - 4xy

( x - y)² = 14² - 180

( x - y)² = 196 - 180

( x - y)² = 16

( x - y) = 4

x + y = 14

x - y = 4

2x = 18

x = 9 .

y = 5 .

14 + 6√5 = √9 + √5 = 3 + √5 .

Answer: 3 + √5 .

Done ✔

A jar contains 666 red jelly beans, 666 green jelly beans, and 666 blue jelly beans.
If we choose a jelly bean, then another jelly bean without putting the first one back in the jar, what is the probability that the first jelly bean will be green and the second will be green as well?

Answers

Answer:

666/1998 x 665/1997 = 665/5991    or    0.110999833083

What is the measure of angle AEF

Answers

Answer:

B) 144°

Step-by-step explanation:

<AEC=108

<EDG= 180-108=72

<DEF=180-72=108

<AEF=360-108-108=144

What is the measure of arc PSR? *

75 degrees
260 degrees
65
100

Answers

Answer:

it most likely would be 260 degrees

Which graph represents the line that has a -intercept of 3 and goes through the point (2, 5) ?

Answers

Answer:

The second one

Step-by-step explanation:

Answer:

Is the third one,as you can see it goes thru the point (2,5)

Step-by-step explanation:

Someone help please I can’t seem to get this one and its my last one

Answers

Answer:

345 cm squared I believe

I'm not 100% sure

Other Questions
If more reactants are used in a chemical reaction, more products will beproduced. This is because *1 pointMore reactants have more atoms to react to form more productsMore reactants take up the same volumeToo many products can slow down the reactionMore reactants cause the reaction to heat up A salesperson works 40 hours per week at a job where has two options for being paid. Option A is an hourly wage of $20. Option B is a commission rate of 10% on weekly sales. How much does need to sell this week to earn the same amount with the two options?Please help.. One of the legs of a right triangle measures 11 cm and its hypotenuse measures 12 cm. Find the measure of the other leg. If necessary, round to the nearest tenth. Which customer is an internal customer of Eureka Computer Solutions? A. Adrian, a regular buyer of products sold by Eureka Computer Solutions B. Beth, a first-time buyer of a product sold by Eureka Computer Solutions C. Layla, a software engineer employed by Eureka Computer Solutions D. Nowzer, a sales distributor for Eureka Computer Solutions E. Jessica, a prospective customer for Eureka Computer Solutions How do the temperatures on Neptune compare to Earth's temperatures? Help out a young degenerate si en una canasta saben 30 limones Cuantos canastas nesesitamos para guardar 75 ? inversa What does irony add to the story "Lamb to the Slaughter?" i will give brainliest Although bats are not known for their eyesight, they are able to locate prey (mainly insects) by emitting high-pitched sounds and listening for echoes. A paper gave the following distances (in centimeters) at which a bat first detected a nearby insect. 24 41 25 68 53 83 43 63 56 34 45 A button hyperlink to the SALT program that reads: Use SALT. (a) Calculate the sample mean distance at which the bat first detects an insect. (Round your answer to four decimal places.) 48.6364 cm (b) Calculate the sample variance and standard deviation for this data set. (Round your answers to four decimal places.) Variance Standard deviation How many grams are in 2.50 moles of copper? Pharoah Corporation factors $251,700 of accounts receivable with Kathleen Battle Financing, Inc. on a with recourse basis. Kathleen Battle Financing will collect the receivables. The receivables records are transferred to Kathleen Battle Financing on August 15, 2020. Kathleen Battle Financing assesses a finance charge of 2% of the amount of accounts receivable and also reserves an amount equal to 4% of accounts receivable to cover probable adjustments. (b) Assume that the conditions are met for a transfer of receivables with recourse to be accounted for as a sale. Prepare the journal entry on August 15, 2020, for Pharoah to record the sale of receivables, assuming the recourse obligation has a fair value of $5,010. (If no entry is required, select "No Entry" for the account titles and enter 0 for the amounts. Credit account titles are automatically indented when the amount is entered. Do not indent manually.) Need help ASAP answer only if you know!!! PLSSSSSSS HELPPPPPPP I WILL GIVE BRAINLIESTTTTTTTTTT!!!!!!!!!!!!!!!!!!!!!PLSSSSSSS HELPPPPPPP I WILL GIVE BRAINLIESTTTTTTTTTT!!!!!!!!!!!!!!!!!!!!!PLSSSSSSS HELPPPPPPP I WILL GIVE BRAINLIESTTTTTTTTTT!!!!!!!!!!!!!!!!!!!!!PLSSSSSSS HELPPPPPPP I WILL GIVE BRAINLIESTTTTTTTTTT!!!!!!!!!!!!!!!!!!!!!PLSSSSSSS HELPPPPPPP I WILL GIVE BRAINLIESTTTTTTTTTT!!!!!!!!!!!!!!!!!!!!!PLSSSSSSS HELPPPPPPP I WILL GIVE BRAINLIESTTTTTTTTTT!!!!!!!!!!!!!!!!!!In 2-3 sentences, describe the legacy of the californios. Giving brainliest!!!!!!! Jennifer scored 40 points in a game on Saturday. If she scored 50 pointson Sunday then what is the percent increase in the points Jenniferscored? why the way you dress is important A data set has these values: 7,9,9, 11, 11, 11, 11, 13, 13, 15. A histogram ofthe distribution is shown.4Which statement does not describe the data set?3Frequency2A. It has a range of 16.B. It has a median of 11.06 8 10 12 14 16c. It has a mode of 11.OD. It is symmetric. A sum amounted naira 2,590at 10% Per annum for thePeriod of 4 Years. Find the sum What is the slope between the points (-2, -4) and (3, 4)? help me with this please