CBSE NCERT Solutions Chapter 5 Arithmetic Progressions Exercise 5.3 Question 5
5. The first term of an AP is 5, the last term is 45 and the sum is 400. Find the number of terms and the common difference.
First term = a = 5
Last term =
Applying formula, to find sum of n terms of AP, we get
Applying formula, to find sum of n terms of AP and putting value of n, we get