Use app×
QUIZARD
QUIZARD
JEE MAIN 2026 Crash Course
NEET 2026 Crash Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
+1 vote
1.7k views
in Arithmetic Progression by (43.0k points)
closed by

If the arithmetic mean of two numbers is 10 and geometric mean is 6, then the numbers are 

A) 1, 19 

B) 2, 18 

C) 3, 17 

D) 3, 18

2 Answers

+1 vote
by (57.0k points)
selected by
 
Best answer

Correct option is (B) 2, 18

Let both required numbers are a and b.

\(\therefore\) Their arithmetic mean \(=\frac{a+b}2\)

and their geometric mean \(=(ab)^\frac12\)

\(\therefore\frac{a+b}2=10\;\&\;(ab)^\frac12=6\)          (Given)

\(\Rightarrow a+b=20\)      _______________(1)

\(ab=6^2=36\)   _______________(2)

Now, \((a-b)^2=(a+b)^2-4ab\)

\(=20^2-4\times36\)

\(=400-144\)

\(=256=16^2\)

\(\therefore a-b=16\)     _______________(3)

By adding (1) & (3), we get

\((a+b)+(a-b)=20+16\)

\(\Rightarrow2a=36\)

\(\Rightarrow a=\frac{36}2=18\)

\(\therefore b=20-a\)

\(=20-18=2\)    (From (1))

Hence, both numbers are 2 and 18.

+1 vote
by (43.4k points)

Correct option is B) 2, 18

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

...