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A supermarket display consists of boxes of cereal. The bottom row has 27 boxes. Each row has four fewer boxes than the row below it. The display has six rows.

 

(a) Write and use a function to determine how many boxes are in the top row. Show your work.

(b) Use the appropriate formula to determine the number of boxes in the entire display. Show your work.

 Oct 7, 2020
 #1
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1 - a_n = 31 - 4 n 

a(6) =31 - 4*6

a(6) =31 - 24

a(6) = 7 boxes in the top row

 

2 - Sum =6/2 *[2*7 + 4*(6 - 1)]    Use AP Formula for summing them up.

                = 3 * [14 + 20]

                = 3 *   34

                = 102 Cereal boxes on display.

 

3 - Check: 27, 23, 19, 15, 11, 7 = 102 Cereal boxes on display.

 Oct 7, 2020
 #2
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an = 27 - 4(n-1)

a= 27 - 4(6-1)

a= 7

 

Sum6 =   n (a1 + a6 )/2

          =   6 (27+7)/2 = 102 boxes

 Oct 7, 2020

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