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Arithmetic Progression 



Problem 4 of 19 


4. For arithemetic progression S( ) = , then find f( ).










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Arithmetic Progression 
4. For arithemetic progression S( 33 ) = 198 , then find f( 17 ).
We have given `S_33 = 198` and we have to find `f(17) = ?`
We know that, `S_n = n/2 [2a + (n  1)d]`
`S_33 = 33/2 [2a + (33  1)d] = 198`
`=> 33 [a + 16d] = 198`
`=> a + 16d = 6 >(1)`
We know that, `f(n) = a + (n  1)d`
`f(17) = a + (17  1)d`
`=> f(17) = a + 16d`
`=> f(17) = 6` (Using (1))





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