Sign in
Please select an account to continue using cracku.in
↓ →
Join Our JEE Preparation Group
Prep with like-minded aspirants; Get access to free daily tests and study material.
To calculate the Mean Deviation about the Mean for the given frequency distribution, we follow a systematic process involving finding the arithmetic mean first, followed by the absolute deviations.
The mean for grouped data is given by the formula:
$$\bar{x} = \frac{\sum f_i x_i}{\sum f_i}$$
Let's calculate the components:
xi |
fi |
fixi |
5 |
8 |
40 |
7 |
6 |
42 |
9 |
2 |
18 |
10 |
2 |
20 |
12 |
2 |
24 |
15 |
6 |
90 |
Total |
$$N = 26$$ |
$$\sum f_i x_i = 234$$ |
$$\bar{x} = \frac{234}{26} = 9$$
The formula for Mean Deviation is:
$$M.D.(\bar{x}) = \frac{\sum f_i |x_i - \bar{x}|}{\sum f_i}$$
Now, let's find the absolute deviations $$|x_i - 9|$$ and their products with frequencies:
| $$x_i$$ | $$f_i$$ | $$|x_i - 9|$$ | $$f_i |x_i - 9|$$ |
| :--- | :--- | :--- | :--- |
| 5 | 8 | $$|5 - 9| = 4$$ | $$8 \times 4 = 32$$ |
| 7 | 6 | $$|7 - 9| = 2$$ | $$6 \times 2 = 12$$ |
| 9 | 2 | $$|9 - 9| = 0$$ | $$2 \times 0 = 0$$ |
| 10 | 2 | $$|10 - 9| = 1$$ | $$2 \times 1 = 2$$ |
| 12 | 2 | $$|12 - 9| = 3$$ | $$2 \times 3 = 6$$ |
| 15 | 6 | $$|15 - 9| = 6$$ | $$6 \times 6 = 36$$ |
| Total | 26 | | 88 |
Substitute the sums into the formula:
$$M.D.(\bar{x}) = \frac{88}{26}$$
Simplifying the fraction by dividing both numerator and denominator by 2:
$$M.D.(\bar{x}) = \frac{44}{13}$$
Final Answer: C ($$\frac{44}{13}$$)
Click on the Email ☝️ to Watch the Video Solution
Create a FREE account and get:
Predict your JEE Main percentile, rank & performance in seconds
Educational materials for JEE preparation
Ask our AI anything
AI can make mistakes. Please verify important information.
AI can make mistakes. Please verify important information.