Sign in
ui-button
ui-button
If the average of number 148, 146, 144, 142,..... in AP be 125, then the total numbers in the series will be
A) 18
B) 24
C) 30
D) 48
Correct answer:
B) 24
Description for Correct answer:
Given series is 148, 146, 144, 142 .....whose first term and common difference is
\( \Large a = 148,\ d = \left(146 - 148\right) = -2 \)
\( \Large S_{n}=\frac{n}{2}\left[ 2a+ \left(n-1\right)d \right] = 125 \)
=> \( \Large 125n = \frac{n}{2}\left[ 2 \times 148+ \left(n-1\right) \times \left(-2\right) \right] \)
=> \( \Large n^{2}-24n = 0 => n \left(n-24\right)=0 \)
n = 24
Please provide the error details in above question
Report Error
Recent Activities
General Knowledge
More questions and answers on- General Knowledge
Aptitude
More questions and answers on- Aptitude
Number System
More questions and answers on- Number System
Time and Distance
More questions and answers on- Time and Distance
Average
More questions and answers on- Average
Time and work
More questions and answers on- Time and work
Simple and compound interest
More questions and answers on- Simple and compound interest
Mensuration
More questions and answers on- Mensuration
Number series
More questions and answers on- Number series
Pipes and Cisterns
More questions and answers on- Pipes and Cisterns
Linear Equations
More questions and answers on- Linear Equations
Quadratic Equations
More questions and answers on- Quadratic Equations
Simplification
More questions and answers on- Simplification
Approximation
More questions and answers on- Approximation
Word problems
More questions and answers on- Word problems