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

 

 May 16, 2018
 #1
avatar+3994 
+2

Long way:

1st week=$4

 

2nd week=$17

3rd week=$30

.

.

.,

10th week=?

 

4th week=43

5th=56

6th=69

7th=82

8th=95

9th=108

\(\boxed{10th=121}\)

.
 May 16, 2018
 #2
avatar+98044 
+2

Thanks, tertre....If we want  the sum over all 10 weeks........

 

First week  =  $4

The common difference is 13

Last week  =  4 + 13(9)  =  $121

 

So....the sum is

 

[ First week + Last week ]  *   [ Number of weeks  ] / 2  =

 

[ 4 + 121 ] *  [ 10 ] / 2  =

 

125  [ 5 ]   =

 

$625

 

 

cool cool cool

 May 17, 2018

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