Please Help!! Math

posted by .

A display of cans on a grocery shelf consists of 20 cans on the bottom, 18 cans in the next row, and so on in an arithmetic sequence, until the top row has 4 cans. How many cans, in total, are in the display?

  • Please Help!! Math -

    terms of the sequence:
    20 , 18 , 16 ,...4

    So we have a = 20, d = -2 , t(n) = 4

    t(n) = a + (n-1)d
    4 = 20 + (n-1)(-2)
    -16 = -2n + 2
    2n = 18
    n = 9

    so we need sum of 9 terms
    = (9/2)(first + last)= (9/2)(20 + 4) = 108
    or
    Sum(n) = (n/2)(2a + (n-1)d)
    = (9/2)(40 + 8(-2)) = 108

    check:
    term9 = a = 8d
    = 20 + 8(-2) = 20-16 = 4

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math

    7^2006 Solving problems with "to the power of" IT works better if you post a problem you have having difficulty with, and explain what you are having difficulty with. Rob has 124 cans of sweet corn to stack on the shelf.If he puts …
  2. math

    If Jenny built a triangle out of soup cans and there are 4 at the top row she added 2 cans to every next row so there are 8 cans in the second row. How many cans are in the 12th row?
  3. 4th grade math

    A store clerk wants to stack 55 cans of tennis balls in a triangular display. How many cans would be in the bottom row?
  4. trigonometry

    Find the number of cans stacked in a display if there are 30 rows of cans with six on the top row, ten on the second row, 14 on the third row and so on. I know it's the sum of an arithmetic sequence, but I'm not sure exactly what to …
  5. arithmetic

    You have 798 cans in 19 rows. If the cans are placed so that each row as 3 fewer cans than the other how many cans are in the bottom row?
  6. Math

    a grocery clerk nstacks three rows of can of fruit for a display, each of the top two rows has 2 fewer cans than the row beneath it, there are 30 cans altogether, how many cans are in each row?
  7. Algebra/Math

    Can you check these for me. Directions: Find the slope of the line that passes through each pair of points. 1. (3,-8) and (-5,2) Answer: -10/8 2. (-10,-3) and (7,2) Answer: -5,-17 3. (-7,-6) and (3,-6) Answer: 9 4. (8,2) and (8,-1) …
  8. maths

    find a6 for an arithmetic sequence where a1=3x+1 and d=2x+6. 2.A display of cans on a grocery shelf consists of 20 cans on the botton, 18 cans inthe next row, and so on in an arithmic sequence, until the to[p row has four cans. how …
  9. math

    There are eight shelves. How many soup cans a grocery clerk stack if the bottom shelf has 21 cans and each additional shelf has 2 fewer soup cans than the previous shelf?
  10. Math

    The Recycling Department of a fast food chain is planning to have a Christmas Tree Making Contest in preparation of the upcoming Holiday Season. Part of the contest mechanics is to collect soft drinks tin cans and build a Christmas …

More Similar Questions