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Ksju [112]
3 years ago
5

In a theater, there are 15 chairs in the first row, each row has 3 more chairs than the previous row, and there are 15 rows. how

many chairs are there in the theater?
SAT
1 answer:
Nimfa-mama [501]3 years ago
5 0

The 1st row has 15 chairs.

The 2nd row has 15 + 3 = 18 chairs.

The 3rd row has 18 + 3 = 15 + 2•3 = 21 chairs.

The 4th row has 21 + 3 = 15 + 3•3 = 24 chairs.

The pattern continues, so that the n-th row has 15 + (n - 1)•3 = 3n + 12 chairs.

If there are 15 rows, then the total number of chairs is

\displaystyle \sum_{n=1}^{15} (3n + 12) = 3 \sum_{n=1}^{15} n + 12 \sum_{n=1}^{15} 1 = 3\cdot\frac{15\cdot16}2 + 12\cdot15 = \boxed{540}

where we use the formulas

\displaystyle \sum_{n=1}^N 1 = N

\displaystyle \sum_{n=1}^N n = \frac{N(N+1)}2

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Let see if you know long division 3) 461​
WARRIOR [948]

Answer:

461 = dividend

3 = divisor

Explanation:

Step 1:

Start by setting it up with the divisor 3 on the left side and the dividend 461 on the right side like this:

           

   3 ⟌ 4 6 1

Step 2:

The divisor (3) goes into the first digit of the dividend (4), 1 time(s). Therefore, put 1 on top:

       1    

   3 ⟌ 4 6 1

Step 3:

Multiply the divisor by the result in the previous step (3 x 1 = 3) and write that answer below the dividend.

       1    

   3 ⟌ 4 6 1

      3    

Step 4:

Subtract the result in the previous step from the first digit of the dividend (4 - 3 = 1) and write the answer below.

       1    

   3 ⟌ 4 6 1

     - 3    

       1    

Step 5:

Move down the 2nd digit of the dividend (6) like this:

       1    

   3 ⟌ 4 6 1

     - 3    

       1 6  

Step 6:

The divisor (3) goes into the bottom number (16), 5 time(s). Therefore, put 5 on top:

       1 5  

   3 ⟌ 4 6 1

     - 3    

       1 6  

Step 7:

Multiply the divisor by the result in the previous step (3 x 5 = 15) and write that answer at the bottom:

       1 5  

   3 ⟌ 4 6 1

     - 3    

       1 6  

       1 5  

Step 8:

Subtract the result in the previous step from the number written above it. (16 - 15 = 1) and write the answer at the bottom.

       1 5  

   3 ⟌ 4 6 1

     - 3    

       1 6  

     - 1 5  

         1  

Step 9:

Move down the last digit of the dividend (1) like this:

       1 5  

   3 ⟌ 4 6 1

     - 3    

       1 6  

     - 1 5  

         1 1

Step 10:

The divisor (3) goes into the bottom number (11), 3 time(s). Therefore put 3 on top:

       1 5 3

   3 ⟌ 4 6 1

     - 3    

       1 6  

     - 1 5  

         1 1

Step 11:

Multiply the divisor by the result in the previous step (3 x 3 = 9) and write the answer at the bottom:

       1 5 3

   3 ⟌ 4 6 1

     - 3    

       1 6  

     - 1 5  

         1 1

           9

Step 12:

Subtract the result in the previous step from the number written above it. (11 - 9 = 2) and write the answer at the bottom.

       1 5 3

   3 ⟌ 4 6 1

     - 3    

       1 6  

     - 1 5  

         1 1

     -     9

           2

You are done, because there are no more digits to move down from the dividend.

The answer is the top number and the remainder is the bottom number.

Therefore, the answer to 461 divided by 3 calculated using Long Division is:

153

2 Remainder

8 0
3 years ago
Read the quotation from Lincoln Steffens’s The Shame of the Cities. "My purpose was...the see if the shameful facts, spread out
hram777 [196]

The best description of  Steffens' purpose in writing about government is:

  • <u>B. to describe corruption in city and state governments</u>

<u />

According to the quotation from Lincoln Steffen's The Shame of the Cities, we are told that the author feels that the shamelessness of the American people would cause the downfall of the "American pride".

As a result of this, the most likely purpose of writing this is to show the level of corruption which is prevalent in the city and state governments to spur the citizens to revolt against the corruption.

Therefore, the correct answer is option B

Read more here:

brainly.com/question/19292081

5 0
3 years ago
What are groups of organs that work together
Paha777 [63]
A group of organs are called a system
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Researchers use what groups as dependent variable so that they can be certain of how experimental groups are responding
Natasha2012 [34]

Answer:

They use a control group.

Hope this helps :)

5 0
2 years ago
Which major processes were needed for the origin of life on earth? abundance of oxygen and the ozone layer active volcanoes and
Sever21 [200]

Answer:

The major processes needed for the origin of life on Earth were the appearance of the first organic compounds, their assembly into macromolecules, self-replicating properties and separation by means of membranes.

Explanation:

4 0
2 years ago
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