Question:
The mean weight of a group of 10 items is 28 and that of another group of n items is 35. The mean of combined group of 10 + n items is found to be 30. The value of n is
The mean weight of a group of 10 items is 28 and that of another group of n items is 35. The mean of combined group of 10 + n items is found to be 30. The value of n is
Updated On: Jun 23, 2023
- 2
- 4
- 10
- 12
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The Correct Option is B
Solution and Explanation
Combined mean $ = \frac{10 \times 28 + 35 \times n}{10 + n}$
$\Rightarrow \, 30 = \frac{280 + 35n}{10 + n}$
$\Rightarrow \, 300 + 30n = 280 + 35n$
$\Rightarrow \, 5n = 20 \Rightarrow n = 4 $
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Concepts Used:
Mean Deviation
A statistical measure that is used to calculate the average deviation from the mean value of the given data set is called the mean deviation.
The Formula for Mean Deviation:
The mean deviation for the given data set is calculated as:
Mean Deviation = [Σ |X – µ|]/N
Where,
- Σ represents the addition of values
- X represents each value in the data set
- µ represents the mean of the data set
- N represents the number of data values
Grouping of data is very much possible in two ways:
- Discrete Frequency Distribution
- Continuous Frequency Distribution