Alberta Free Tutoring And Homework Help For Math 20-1

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# 14 in the pre calculus textbook in Alberta 

 

suppose a set of 10 beads were laid in a line where each successive bead had a diameter that was 3/4 of the diameter of the previous bead. If the first bead had a diameter of 24mm, determine the total length of the line of the beads. Express your answer to the nearest millimetre.

7 years ago

Answered By Alex V

If I'm understanding this correctly you need to set up a sum series function: 

  $\sum_{x=0}^9=24mm\left(\frac{3}{4}\right)^x$x=09=24mm(34 )x  

Note that the end of the series is 9, because for many series calculations the end of the series is (x-1). 

Plug this formula into your calculator, or an excel sheet if you can, and you should get an answer of 90.59mm which makes the answer: Distance = 91mm.


7 years ago

Answered By Xuezhong J

this is a question about the sum of  geometric series.   In this question, a1=24,  r=3/4,

S10=a1(1-r9)/(1-r),  you can the answer easily using calculator.