Answer: First Option : Sₙ= n/2(a₁ + aₙ)
Step-by-step explanation:
The nth partial sum of an arithmetic sequence or the sum of the first n terms of the arithmetic series can be defined as the sum of a finite number of term in an arithmetic sequence.
It is calculated using the formula:
Sₙ= n/2(a₁ + aₙ)
Where :
a₁ = First term
aₙ = last term
n = number of terms
The answer is B because its a square so all sides are equal and then you factor
Your answer is 0.45 I think
Here you go! Hope this helps!
The percentage that the number of airlines with an average airplane age of 14 is less than the number of airlines with an average airplane age of 11 is:
B. 20%.
<h3>What is a percentage?</h3>
The percentage of an amount a over a total amount b is given by a multiplied by 100% and divided by b, that is:

The percentage of airlines with an average age of 14 years is:

The percentage of airlines with an average age of 11 years is:

The difference is:
33.33% - 13.33% = 20%.
Hence option B is correct.
More can be learned about percentages at brainly.com/question/10491646
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