Answer:
3rd option : 1455
Step-by-step explanation:
here, a = 5, d = 3 , tn = 92, n = ?, Sn = ?
tn = [a + (n - 1) d]
92 = [ 5 + (n - 1)d
92 = 5 + 3n - 3
92 - 5 + 3 = 3n
90 = 3n
n = 90/3
n = 30
By sum of first n terms of an A. P formula,
Sn = n/ 2 [ 2a + (n - 1) d]
Sn = 30/2 [ 2 * 5 + (30 - 1) 3]
Sn = 15[ 10 + 29 ( 3) ]
Sn = 15[ 10 + 87 ]
Sn = 15( 97 )
Sn = 15 * 97
Sn = 1455
Therefore, option 3rd 1455 is correct.
