SOLUTION: pick right chioce for each thank u Question 9 You can do 10 situps at the beginning of the month. You add 1 additional situp everyday. How may TOTAL situps have you done af

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Question 82551: pick right chioce for each thank u
Question 9
You can do 10 situps at the beginning of the month. You add 1 additional situp everyday. How may TOTAL situps have you done after 30 days?
a. 10
b. 30
c. 735
d. 1030

Question 10
You drive a 12 inch spike into a piece of wood 1/3 of the way with each strike of the hammer. How far has the spike gone into the wood (total) after the 3rd hit of the hammer? Round your answer to the nearest tenth.
a. 3.6 inches
b. 0.4 inches
c. 8.4 inches
d.12 inches
e. 11.6 inches

Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
(c)735
Just add up all the situps
If you never increased the number each day, how many
would you have?
10 + 10 + 10 + 10 + ... for 30 days, or 10*30 = 300
To this you want to add 1 + 2 + 3 + 4 + ... + 30
Adding this sequence up to 10 gives you 55
Now 11 + 12 + 13 + 14 + ... + 20 is 55 plus 10*10
or 55 + 100 = 155
And 21 + 22 + 23 + 24 + ... + 30 is 55 + 10*20
or 55 + 200 = 255
adding up
300 + 55 + 155 + 255 = 765 answer
(c)8.4 in
With the 1st hit, the spike is driven in
in
Now there are 8 inches of spike above the wood
The 2nd hit drives it in
in
So far the spike has been driven in
in
That means there are in above the wood
So, with the 3rd strike, it is driven in
in
So, in total, it's been driven in
in