If the average of the numbers 148, 146, 144, 142, ... in AP, be 125, then the total numbers in the series will be

Given series is 148, 146, 144, 142, ... whose first term and common difference isa=148,d=(146−148)=−2Sn=n2[2a+(n−1)d]=125n (given) ⇒125n=n2[2×148+(n−1)×(−2)]⇒n2−24n=0⇒n(n−24)=0⇒n=24        (n≠0)