Question

19. 200 logs are stacked in the following manner: 20
logs in the bottom row, 19 in the next row, 18 in
the row next to it and so on (see Figure). In how
many rows are the 200 logs placed and how many
logs are in the top row?
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Answer 1

Answer:

Hey mate here's your answer.

Answer 2

Answer:

listen dude stop me where you don't get this

Step-by-step explanation:

First of all,

You should know that an AP is formed in this question

AP-20,19,18-------

Now, we know that total logs=200

so, the sum of all these logs=200

we have to find no. of rows... that is we have to find 'n'

and also the logs in last row i.e we have to find 'An'

Sn=200

a=20

d=19-20=-1

Sn=n/2[ 2a+(n-1)d]

200=n/2[40 +(n-1)(-1)]

400=n× (40-n+1)

400=41n-n^2

Dividing equation by -1

n^2-41n=-400

n^2-41n+100=0

Idk about the answer

but i hope you learned how to solve this

when you'll solve this you'll get two value of n... but obviously n cannot be negative because it is a count of something so you'll reject negative value

and then, you can find An because you know n now

HOPE IT HELPS:)

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Andd still if you have some doubt regarding this... start typing on any of my question incompleted.. when I'll get a notification I'll try to help you out there