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Hello, I have an answer to this question but my classmates have answered have all had different answers than me. I just want to make sure that I am correct. 

 

Heres the question:

Andrew earns an allowance of $14 the first week, $17 the next week, $20 the following week, and so on.

How much will Andrew earn over the course of 10 weeks?

 

My answer--$42

My reasoning--Because the series increases by 3. Sooo 14+3=17+3=20+3=23+3=26 and so on until you add 3 to the number (n) 10 times. Which equals 42. 

Am I right?

Guest Apr 15, 2018
 #1
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The answer is  given by :

 

[ First term + Last term] * 10 / 2

 

The frist term is 14

The last  is  14 + 3(10 -1)  =  14 + 3(9) =  41    ....  so  we have.......

 

[ 14 + 41 ] * 10 / 2  =

 

[55 * 10]  / 2  =

 

$275

 

 

cool cool cool

CPhill  Apr 15, 2018

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