# An AP 8, 10, 12, ... has 60 terms. Find its last term. Hence, find the sum of its last 10 terms.

Here, First term = a = 8

Common difference = d = 10 - 8 = 2

No. of terms = 60

last term will be 60th term.

Using the formula for finding nth term of an A.P.,

l = a60 = a + (60 - 1) × d

l = 8 + (60 - 1) × 2

l = 8 + 118 = 126

Now, sum of last 10 terms = sum of first 60 terms - sum of first 50 terms

i.e. sum of last 10 terms = S60 - S50

Now, Sum of first n terms of an AP is

Sn = [2a + (n - 1)d]

Sum of first 50 terms is given by:

S50 = [2(8) + (50 - 1)(2)]

= 25 × [16 + 98]

= 25 × 114

= 2850

Now, Sum of first 60 terms is given by:

S60 = [2(8) + (60 - 1)(2)]

= 30 × [16 + 118]

= 30 × 248

= 4020

Now, S60 - S50 = 4020 - 2850

= 1170

last term = 126, sum of last 10 terms = 1170

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Champ Quiz | Arithmetic Progression34 mins
Champ Quiz | Arithmetic Progression30 mins
Lets Check Your Knowledge in A.P.49 mins
Arithmetic progression: Previous Year NTSE Questions34 mins
Quiz on Arithmetic Progression Quiz32 mins
Arithmetic Progression Tricks and QUIZ37 mins
Quiz | Group of Questions on General Term of an A.P49 mins
Become a Master of A.P. in 45 Minutes!!47 mins
Get to Know About Geometric Progression41 mins
NCERT | Solving Questions on Introduction of A.P42 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses