All Exams Test series for 1 year @ ₹349 only
Question

If the mean of 20 observations, namely \(x_1, x_2, x_3, \dots, x_{20}\) is 1.414, then what is the value of \(\sum_{i=1}^{20} 100(2x_i + 4)\) ?

This question was previously asked in
NDA 1 2026 GAT Question Paper (12-Apr-2026)
The correct answer is

13656 

Summation Calculation from Mean

This solution details the calculation for a summation expression, using the provided mean of observations.

Step 1: Calculate Sum of Observations

We are given 20 observations (\(x_1, \dots, x_{20}\)) with a mean \(\bar{x}=1.414\). The mean formula is \( \bar{x} = \frac{\sum_{i=1}^{n} x_i}{n} \).

Using the given values (\(n=20\)):

\( \sum_{i=1}^{20} x_i = n \times \bar{x} = 20 \times 1.414 = 28.28 \)

Step 2: Evaluate the Summation Expression

We need to find the value of \(\sum_{i=1}^{20} 100(2x_i + 4)\). We apply summation properties:

1. Factor out the constant 100:

\( 100 \sum_{i=1}^{20} (2x_i + 4) \)

2. Split the summation and simplify:

\( 100 \left( \sum_{i=1}^{20} 2x_i + \sum_{i=1}^{20} 4 \right) \)

3. Use the sum of \(x_i\) and the sum of a constant (\( \sum_{i=1}^{n} c = n \times c \)):

\( 100 \left( 2 \sum_{i=1}^{20} x_i + (20 \times 4) \right) \)

4. Substitute the calculated sum \(\sum_{i=1}^{20} x_i = 28.28\) and calculate:

\( 100 \left( 2 \times 28.28 + 80 \right) \) \( = 100 \left( 56.56 + 80 \right) \) = 100 (136.56) = 13656

Final Answer

The calculated value of the summation is 13656.

Was this answer helpful?

Similar Questions

  1. What is \(\sum_{i=1}^n x_i f_i\) equal to ?
  2. What is the mean of the distribution ?
  3. What is the mean deviation of the largest five observations ?
  4. What is the variance of the largest five observations ?
  5. Which one of the following is correct?

  6. Which one of the following statements is correct?

  7. What is the total number of students whose height is less than or equal to 165 cm?

  8. What is the median height of the class?

  9. The height which occurs most frequently in the class is

  10. The most appropriate graphical representation of the given frequency distribution is


Important Questions from Statistics

  1. If the value of x is taken as 25 and a pie chart is drawn, what will be the central angle of the field showing the number of students who got marks in the interval 30-40?

  2. If the mean marks of the students is 27.5, then what is the value of x?

  3. Match the following:

    (a) Marginalist Revolution(i) Samuelson
    (b) Multiplier-Accelerator model(ii) J. R. Hicks
    (c) IS-LM curves(iii) Jevous
    (d) Real Business Cycle(iv) Robert J. Borro

    Choose the correct option from those given below:

  4. As per the SRS Bulletin of September 2017, the estimated death rate for Kerala is 7.6, while for Bihar it is 6. From these data which is the correct inference to draw?

  5. Arrange the following States in descending order according to Maternal Mortality Ratio (MMR) as per the Special Bulletin of SRS, May, 2018:

    (i) Assam

    (ii) Bihar

    (iii) Madhya Pradesh

    (iv) Uttar Pradesh

    Choose the correct answer from the code given below :

Need Expert Advice?
Upcoming Exams
NDA
September 13, 2026
CDS
September 13, 2026
Test Series
NDA img
Defence
NDA 2026 Mock Test Series (Latest Pattern)
501 Tests 1 Tests Free
882 Attempts
4.6(131)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App