Home
Class 12
MATHS
The ratio of the variance of first n pos...

The ratio of the variance of first n positive integral multiples of 4 to the variance of first n positive odd number is

Text Solution

AI Generated Solution

The correct Answer is:
To find the ratio of the variance of the first \( n \) positive integral multiples of 4 to the variance of the first \( n \) positive odd numbers, we can follow these steps: ### Step 1: Identify the first \( n \) positive integral multiples of 4 The first \( n \) positive integral multiples of 4 are: \[ 4, 8, 12, \ldots, 4n \] This can be expressed as: \[ x_i = 4i \quad \text{for } i = 1, 2, \ldots, n \] ### Step 2: Calculate the variance of the multiples of 4 The variance \( \sigma_x^2 \) of a dataset is given by: \[ \sigma^2 = \frac{1}{n} \sum_{i=1}^{n} (x_i - \bar{x})^2 \] Where \( \bar{x} \) is the mean of the dataset. First, we calculate the mean \( \bar{x} \): \[ \bar{x} = \frac{1}{n} \sum_{i=1}^{n} 4i = \frac{4}{n} \cdot \frac{n(n+1)}{2} = 2(n+1) \] Now, we calculate the variance: \[ \sigma_x^2 = \frac{1}{n} \sum_{i=1}^{n} (4i - 2(n+1))^2 \] This can be simplified using the property of variance. Since we can factor out the constant: \[ \sigma_x^2 = 4^2 \cdot \sigma^2 \quad \text{(where } \sigma^2 \text{ is the variance of the first } n \text{ natural numbers)} \] ### Step 3: Variance of the first \( n \) natural numbers The variance of the first \( n \) natural numbers \( 1, 2, 3, \ldots, n \) is: \[ \sigma^2 = \frac{(n^2 - 1)}{12} \] Thus, the variance of the multiples of 4 becomes: \[ \sigma_x^2 = 16 \cdot \frac{(n^2 - 1)}{12} = \frac{4(n^2 - 1)}{3} \] ### Step 4: Identify the first \( n \) positive odd numbers The first \( n \) positive odd numbers are: \[ 1, 3, 5, \ldots, (2n-1) \] ### Step 5: Calculate the variance of the odd numbers The mean \( \bar{y} \) of the first \( n \) odd numbers is: \[ \bar{y} = \frac{1}{n} \sum_{i=1}^{n} (2i - 1) = \frac{1}{n} \cdot n^2 = n \] Now, we calculate the variance: \[ \sigma_y^2 = \frac{1}{n} \sum_{i=1}^{n} ((2i - 1) - n)^2 \] Using the same property of variance: \[ \sigma_y^2 = 2^2 \cdot \sigma^2 = 4 \cdot \frac{(n^2 - 1)}{12} = \frac{n^2 - 1}{3} \] ### Step 6: Calculate the ratio of the variances Now we can find the ratio of the variances: \[ \text{Ratio} = \frac{\sigma_x^2}{\sigma_y^2} = \frac{\frac{4(n^2 - 1)}{3}}{\frac{(n^2 - 1)}{3}} = \frac{4(n^2 - 1)}{(n^2 - 1)} = 4 \] ### Final Answer The ratio of the variance of the first \( n \) positive integral multiples of 4 to the variance of the first \( n \) positive odd numbers is: \[ \boxed{4} \]
Promotional Banner

Similar Questions

Explore conceptually related problems

The variance of the first 20 positive integral multiples of 4 is equal to

The variance of first 20 - natural numbers is

The variance of first n natural number is:

Find the variance of first 50 even natural numbers.

If the variance of first n natural numbers is 2 and the variance of first m odd natural numbers is 40, then m +n =

If the variance of first n even natural numbers is 133, then the value of n is equal to

The variance of the first 50 even natural numbers is

Find the sum of the first n odd numbers

Find the sum of the first n odd numbers

Find the variance of first 10 multiples of 3