Question

Find the number of terms in A.P. If sum of these terms is 710 and first and last terms are 7 and 64 respectively:

Answer 1

Answer:

Total no. of terms are 20

Step-by-step explanation:

We are given that Sn =710

And a(first term) = 7 and l(last term)=64

And formula of Sn = n/2 (a+l)

=> 710 = n/2 (7+64)

=> solving it 710(2)/71 =n

we get our ans. n=20

Answer 2

Answer:

Number of terms in an A.P is 20.

Step-by-step explanation:

Given : If sum of these terms is 710 and first and last terms are 7 and 64 respectively:

To find : The number of terms in A.P.?

Solution :

We have given that,

$S_n=710$

First term a=7

Last term l=64

Applying sum formula of an A.P.

$S_n=\frac{n}{2}[a+l]$

Substitute the values,

$710=\frac{n}{2}[7+64]$

$710=\frac{n}{2}[71]$

$n=\frac{710\times 2}{71}$

$n=20$

Therefore, Number of terms in an A.P is 20.