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Question

What is the difference between the average of first 50 even natural numbers and the average of first 50 odd natural numbers ?

This question was previously asked in
CDS 2 2024 Maths Question Paper (01-Sep-2024)
The correct answer is
1

Finding the Difference Between Averages

This solution explains how to find the difference between the average of the first 50 even natural numbers and the average of the first 50 odd natural numbers.

Calculating the Average of First 50 Even Natural Numbers

The first 50 even natural numbers are:

2, 4, 6, 8, ..., up to the 50th even number.

The sequence of the first \(n\) even natural numbers is \(2, 4, 6, \dots, 2n\). In this case, \(n=50\), so the 50th even number is \(2 \times 50 = 100\). The sequence is \(2, 4, 6, \dots, 100\).

To find the average of an arithmetic sequence, we can use the formula:

\( \text{Average} = \frac{\text{First Term} + \text{Last Term}}{2} \)

Applying this formula:

\( \text{Average}_{\text{even}} = \frac{2 + 100}{2} = \frac{102}{2} = 51 \)

Alternatively, the average of the first \(n\) even natural numbers is given by the formula \(n+1\). For \(n=50\), the average is \(50 + 1 = 51\).

Calculating the Average of First 50 Odd Natural Numbers

The first 50 odd natural numbers are:

1, 3, 5, 7, ..., up to the 50th odd number.

The sequence of the first \(n\) odd natural numbers is \(1, 3, 5, \dots, 2n-1\). In this case, \(n=50\), so the 50th odd number is \(2 \times 50 - 1 = 100 - 1 = 99\). The sequence is \(1, 3, 5, \dots, 99\).

Using the same average formula for an arithmetic sequence:

\( \text{Average}_{\text{odd}} = \frac{\text{First Term} + \text{Last Term}}{2} \)

Applying this formula:

\( \text{Average}_{\text{odd}} = \frac{1 + 99}{2} = \frac{100}{2} = 50 \)

Alternatively, the average of the first \(n\) odd natural numbers is simply \(n\). For \(n=50\), the average is \(50\).

Calculating the Difference

The question asks for the difference between the average of the first 50 even natural numbers and the average of the first 50 odd natural numbers.

\( \text{Difference} = \text{Average}_{\text{even}} - \text{Average}_{\text{odd}} \)

\( \text{Difference} = 51 - 50 \)

\( \text{Difference} = 1 \)

Conclusion

The difference between the average of the first 50 even natural numbers and the average of the first 50 odd natural numbers is 1.

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  1. All possible groups of 3 distinct numbers from among A, B, C, D and E are formed. If the aggregate of sums of numbers of each group is 120, then what is the arithmetic mean of A, B, C, D and E ?

Important Questions from Average

  1. The average height of 20 students of class 8 is 152 cm and the average height of 15 students of class 9 is 168 cm. What is the average height (to the nearest cm) of the students of both classes?

  2. The average of 4, 6, 8, 12 and x is 7 and the average of x, 9, 13, 15 and y is 9. What is the value of 2x - 3y?

  3. The average weight of 20 girls in a school was 52 kg. Two new students of weight 54 kg and 50 kg were admitted. The ratio of this new average to the old one is:

  4. If the average of two numbers is 13 and the square root of their product is 12, then the difference between the numbers is:

  5. If the average of 5 consecutive odd integers in increasing order is 11 , then the average of the last 3 of them is:

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