Question :

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.

Subject

Maths

Standard

Class 10

Views

1790

Asked By

Emily

Pari
Answer / Solution

Solution: Given that,
first term, a = 5
last term, l = 45
Sum of the AP, Sn = 400

As we know, the sum of AP formula is;
Sn = n/2 (a + l)
400 = n/2 (5 + 45)

400 = n/2 (50)
Number of terms, n = 16

As we know, the last term of AP series can be written as;
Last term, l = a + (n − 1) d
45 = 5 + (16 − 1) d
40 = 15d
Therefore,

Common difference, d = 40/15 = 8/3

Recent Question Update

Advantages Of NCERT, CBSE & State Boards Solutions For All Subjects

  • All the NCERT Solutions have been prepared by academic experts having 10+ years of teaching experience.
  • They have prepared all the solutions in simple and easy language so that each and every student can understand the concepts easily.
  • All the solutions have been explained step to step-wise in details with better explanations.
  • Students can also use these question and answers for your assignments and in homework help.
  • All the solutions have been explained in detail and the answers have been compiled in a step-wise manner.
  • All the questions and answers are commonly prepared according to the Latest Syllabus of Board Education and Guidelines.
  • Students can know about the various types of questions asked in the exams with the help of these solutions.

Top Course Categories