Question

what is the Arithmetic mean of first 20 terms of an Arithmetic progression whose first term is 5 and fourth term is 20​

Answer 1

Answer:

100 is the answer

Step-by-step explanation:

a=5

a4= 5+(4-1)d= 20

5+3d=20

3d=15

d=5

therefore

a20= 5 +(20-1)5

= 5+(19×5)

=5+95

=100