Question

which term of the AP: 3,8,13,18....,is 78?

Answer 1

The answer 16th term of an Ap

Answer 2

Given A. P. is 3,8,13,18,...
T1=3,T2=8,T3=13,T4=18
T2-T1=8-3=5
T3-T2=13-8=5
Therefore, T2-T1=T3-T2=5=d
Using, Tn=a+(n-1)d
or 78=3+(n-1)5
or 5(n-1)=78-3
or n-1=75/5=15
or n=15+1=16
Hence,16th term of given A. P. is 78.Ans.