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3 years ago

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Help???? i will be so greatfull

1 answer:

Stolb23 [73]3 years ago

7 0

I 150
ii 200
iii 350
i 50
ii 200
iii 250

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1. Find the sum of the series (IMAGE) . Show your work.

pav-90 [236]

<u>QUESTION 1 ANSWER</u>

The series is

$\sum_{n=1}^{15}{ (2n-1)}$

So the nth term of this sequence is

$U_n=2n-1$

We generate some few terms of the sequence as follows:

When $n=1$ ,

The first term of the sequence becomes,

$U_1=2(1)-1$

$U_1=1$

When $n=2$ ,

$U_2=2(2)-1$

$U_2=3$

When $n=3$ ,

$U_2=2(3)-1$

$U_2=5$

The constant difference is $d=2$ .

The sum of the series is given by,

$S_n=\frac{n}{2}(2a+(n-1)d)$

There are 15 terms in the series, therefore $n=15$

$S_{15}=\frac{15}{2}(2(1)+(15-1)2)$

$S_{15}=\frac{15}{2}(2+14(2))$

$S_{15}=\frac{15}{2}(30)$

$S_{15}=15\times 15$

$S_{15}=225$

<u>ANSWER TO QUESTION 2</u>

The bottom row has $23$ boxes. This means $a=U_1=23$

a) Since each row has 3 fewer boxes $d=-3$ .

The nth row is given by,

$U_n=23+(n-1)\times(-3)$

$U_n=23+-3n+3$

$U_n=23-3n$

The top row is the 6th row, meaning $n=6$ .

$U_6=23-3(6)$

$U_6=23-18$

$U_6=5$

b) The number of boxes in the entire display is given by

$S_n=\frac{n}{2} (a+l)$

Where $a=23$ , the first term(row) and $l=5$ , the last term(row).

Since there are 6 rows,

$S_6=\frac{6}{2} (23+5)$

$S_6=3 (28)$

$S_6=84$

<u>ANSWER TO QUESTION 3</u>

The number of visitors in the first week is $a=5$ .

Since the number of visitors each week is doubled the number of visitors in the subsequent weeks, the sequence is a geometric progression with a common ratio of $r=2$ .

The general term of a geometric sequence is

$U_n=ar^{n-1}$

So in the 8th week, we have

$U_8=5\times 2^{8-1}$

$U_8=5\times 2^{7}$

$U_8=5\times 128$

$U_8=640$

Hence 640 people visited the website in the 8th week

4 0

3 years ago

Hey I am new-<br><br><br><br>nvm what is radius?

DENIUS [597]

Answer:

a straight line from the center to the circumference of a circle or sphere.

Step-by-step explanation:

7 0

3 years ago

Select the expression equivalent to (2.1x + 4.3) - (-3x - 7)

Andrew [12]

X= 5.1x+11.3
Explanation : combine like terms which is 5.1x and 3x and you get the answer D!

4 0

3 years ago

Read 2 more answers

Joan and her brother Justin left a hotel at the same time, driving in opposite directions at constant rates. After traveling for

inessss [21]

Answer:

Joan drive with a speed of 55 miles per hour.

Step-by-step explanation:

Given:- Travelling time (t) = 4 hours.

Travelled distance (d) = 480 miles.

Speed of Justin is 10 miles per hour faster than Joan.

To find:- Speed of Joan = ?

Solution:-

Let speed of Joan be x,

therefore speed of Justin = x+10 ---------------(from given)

Now, Total speed of Joan and Justin = x+x+10

Total speed of Joan and Justin = 2x+10 ------------(1)

Now formula for speed is,

Speed = $\frac{distance}{time}$

$2x+10=\frac{480}{4}$ -------------(from 1 and given)

$2x+10=120$

$2x=120-10$

$2x=110$

$\therefore x=\frac{110}{2}$

$\therefore x= 55$

as x is the speed of Joan,

Therefore Joan drive with a speed of 55 miles per hour.

6 0

3 years ago

Read 2 more answers

What is the value of x?

GenaCL600 [577]

Answer:

<h2>x = 3</h2>

Step-by-step explanation:

Look at the picture.

We have the triangles 45° - 45° - 90° and 30° - 60° - 90°.

The sides of those triangles are in ratio:

1 : 1 : √2 and 1 : √3 : 2

Therefore

If AC = 6√2 then AB = BC = 6

If BC = 6 then x = 6 : 2 = 3

7 0

4 years ago