Join WhatsApp Icon CAT WhatsApp Group
Question 10

If the sum of the first 11 terms of an arithmetic progression equals that of the first 19 terms, then what is the sum of the first 30 terms?

Solution

Share

Sum of the first 11 terms = 11/2 ( 2a+10d) 

Sum of the first 19 terms = 19/2 (2a+18d) 

=> 22a+110d = 38a+342d => 16a = -232d

=> 2a = -232/8 d = -29d

Sum of the first 30 terms = 15(2a+29d) = 0

Video Solution

video
View More Questions From Progressions and Series

Create a FREE account and get:

  • All Quant CAT complete Formulas and shortcuts PDF
  • 38+ CAT previous year papers with video solutions PDF
  • 5000+ Topic-wise Previous year CAT Solved Questions for Free

CAT Quant Questions | CAT Quantitative Ability

CAT Arithmetic QuestionsCAT Percentages QuestionsCAT Time And Work QuestionsCAT Profit And Loss QuestionsCAT Number Series Questions

CAT DILR Questions | LRDI Questions For CAT

CAT Arrangement QuestionsCAT Miscellaneous LR QuestionsCAT Quant Based LR QuestionsCAT DI Miscellaneous QuestionsCAT Quant Based DI Questions

CAT Verbal Ability Questions | VARC Questions For CAT

CAT Miscellaneous QuestionsCAT Para Summary QuestionsCAT Reading Comprehension QuestionsCAT Grammar and Sentence Correction QuestionsCAT Verbal Ability Questions

Free CAT Quant Questions

CAT Quadratic Equations

CAT Arithmetic

CAT Averages Mixtures Alligations

CAT Logarithms

CAT Linear Equations

CAT Venn Diagrams

CAT Coordinate Geometry

CAT Functions, Graphs and Statistics

CAT Data Sufficiency

CAT Time, Speed and Distance

CAT Averages

CAT Progressions and Series

CAT Geometry

CAT Number Series

CAT Mensuration

CAT Number Systems

CAT Simple Interest Compound Interest

CAT Probability, Combinatorics

CAT Time Speed Distance

CAT Percentages

CAT Inequalities

CAT Algebra

CAT Profit And Loss

CAT Time And Work

CAT Logarithms, Surds and Indices

CAT Profit and Loss

CAT Averages, Ratio and Proportion

CAT Remainders

Related Formulas With Tests

A.P. - Formulas and Properties