Question

A-b) = la-6).
4. There are n arithmetic means between 3 and 17. The ratio of the first mean to the last mean
is 1:3. Find n.​

Answer 1

Answer:

3,a

1

,a

2

,....a

n

,17ϵA.P.(n+2 terms)

⇒3,3+d,a

2

,a

2

.....17−d,17ϵA.P.

⇒

3+d

17−d

=

1

3

∴17−d=9+3d⇒d=2

Now a+(n+1)d=t

n+2

=17

⇒3+(n+1)(2)=17⇒n=6

Hence choice (b) is correct.