A skier has decided that on each trip down a slope, she will do 2 more jumps than before. On her first trip she did 6 jumps. Derive the sigma notation that shows how many total jumps she attempts from her fourth trip down the hill through her twelfth trip. Then solve for how many total jumps she attempts from her fourth trip down the hill through her twelfth trip.

Question

anonymous · Answer

http://assets.openstudy.com/updates/attachments/5341b17be4b02f8a3bd596aa-melissaholmes-1396814358820-summation.....png

anonymous · Answer

@jhonyy9

snowsurf · Answer

On her first trip she done 6 jumps. Each trip she does she does 2 more jumps. If we create a table you can start to see a pattern.

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anonymous · Answer

so she attempts 8 jumps from her 4th step

anonymous · Answer

i mean trip

snowsurf · Answer

You can see its increasing by 2. So we have 2x where x is the number of trips. But we know from her first trip she done 6 jumps. If we have x =1 so that its the first trip we get 2 but we need to add 4 to get a total of 6 jump from her first trip.
So we have $$\sum_{1}^{12}= 2x + 4$$

snowsurf · Answer

No she does not attempt 8 jumps. Because you need to take the sum to get it, that table is to show you the pattern to derive that formula you see in your multiple choice. So lets see how many jumps she did do.

To find the total of jumps from 4 through 12 we rewrite the sigma notation as 
$$\sum_{4}^{12} = 2x+4$$

snowsurf · Answer

So see if you can use this formula to find the total number of jumps from 4 trips through 12.

anonymous · Answer

ok

anonymous · Answer

im not sure if i did it right but i got 180

snowsurf · Answer

Yes that is correct