Q. 18

The sum of first five multiples of 3 is
A. 45

B. 55

C. 65

D. 75

Answer :

The first five multiples of 3 are 3, 6, 9, 12 and 15.


Here, first term, a = 3, common difference, d = 6 – 3 = 3 and number of terms, n = 5


Using the formula,



Where Sn is the sum of first n terms


n = no of terms


a = first term


d = common difference


S5 = (5/2)[ 2(3) + (5 - 1)(3)]


= (5/2)[ 6 + 12]


= 5(9)


= 45

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 ProgressionChamp Quiz | Arithmetic ProgressionChamp Quiz | Arithmetic Progression34 mins
Champ Quiz |  Arithmetic ProgressionChamp Quiz |  Arithmetic ProgressionChamp Quiz | Arithmetic Progression30 mins
Quiz | Arithmetic ProgressionQuiz | Arithmetic ProgressionQuiz | Arithmetic Progression44 mins
Lets Check Your Knowledge in A.P.Lets Check Your Knowledge in A.P.Lets Check Your Knowledge in A.P.49 mins
NCERT | Fundamental Theorem Of ArithmeticNCERT | Fundamental Theorem Of ArithmeticNCERT | Fundamental Theorem Of Arithmetic45 mins
Arithmetic progression: Previous Year NTSE QuestionsArithmetic progression: Previous Year NTSE QuestionsArithmetic progression: Previous Year NTSE Questions34 mins
NCERT | Questions on General Term of an A.PNCERT | Questions on General Term of an A.PNCERT | Questions on General Term of an A.P47 mins
Quiz on  Arithmetic Progression QuizQuiz on  Arithmetic Progression QuizQuiz on Arithmetic Progression Quiz32 mins
NCERT | Arithmetic ProgressionNCERT | Arithmetic ProgressionNCERT | Arithmetic Progression36 mins
Get to Know About Geometric ProgressionGet to Know About Geometric ProgressionGet to Know About Geometric Progression41 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
caricature
view all courses