Exercise 13.1: Mean of Grouped Data
Calculate the mean of grouped data using three methods. The step-deviation method is fastest for large numbers.
Extra Practice Questions
These questions cover the same concepts as Exercise 13.1. Try solving them to build confidence before or after the textbook exercise.
What does 'cumulative frequency' mean?
The median divides the total frequency into:
The marks distribution of 24 students is: | $10-25$ | $25-40$ | $40-55$ | $55-70$ | $70-85$ | with frequencies 2, 3, 7, 6, 6. Find the median class and the median.
If each observation of a data set is increased by 5, then the mean:
Find the mean using the direct method for the following data: | Class | $0-10$ | $10-20$ | $20-30$ | $30-40$ | | Frequency | 5 | 8 | 12 | 5 |
A 'less than' ogive is a graph of cumulative frequency plotted against:
The mode of the data: 2, 3, 4, 5, 3, 3, 4, 2, 3 is:
Using the assumed mean method with $a = 25$, find $\sum f_i d_i$ if the class marks are 5, 15, 25, 35, 45 with frequencies 6, 10, 12, 8, 4.
The mean of the first 5 natural numbers is:
In a frequency distribution, the sum of $f_i x_i = 420$ and $\sum f_i = 30$. The mean is:
Stuck on a question?
Paste any question from Exercise 13.1 into our AI Maths Solver and get a step-by-step solution instantly. It works for all NCERT questions.
Try AI Solver — FreeCommon Mistakes to Avoid
- ✗Not finding class marks (midpoints) correctly
- ✗Errors in the assumed mean method — forgetting to add back the assumed mean
- ✗Incorrect step-deviation when class width isn't uniform
Other Exercises in Chapter 13
Frequently Asked Questions
How many questions are in Exercise 13.1?
Exercise 13.1 has 9 questions on finding the mean of grouped data using direct, assumed mean, and step-deviation methods.
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