This is the Important question based on Arithmetic progression Chapter of R.S Aggarwal book for ICSE & CBSE Board.
In this Question the first term, last term and the sum of the terms is given
you have to find the common difference.
Question Number 31 Of Exercise 11 C of RS Aggarwal Solution.
Deepak BoraNewbie
In an AP the first term is 2, the last term is 29 and sum of the terms is 155, Find the common difference of the AP. Hint = S_n=n/2 (a+l) = n/2 (2+29) = 155 = n=10 T_a= a+(n-1)d = 2+9d = 29 = d=3
Share
a = 2
l = 29
Sn = 155
Sn = n/2 (a+1)
155 = n/2 (2+29) = 31 n/2
n = 155 x 2 / 31 = 10
: – l = a + (n-1) d
29 = 2 + (10-1) d
27 = 9 d
Hence , d = 3