Better Students Ask More Questions.
(a) An arithmetic progression contains 25 terms and the ﬁrst term is −15. The sum...
1 Answer | add yours
The data given in the question as follows.
`a = -15`
`n = 25`
`S_n = 525`
The sum of the arithmetic series given as;
`S_n = (n/2) (2a+(n-1)d)`
`525 = (25/2) (-15*2 + (25-1)d)`
`1050 = 25(-30+24d)`
`42+30 = 24d`
So the common difference is 3.
Posted by jeew-m on September 4, 2013 at 5:14 PM (Answer #1)
Join to answer this question
Join a community of thousands of dedicated teachers and students.