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The average marks of some students in a class is 43. When 4 students are included the average becomes 42.5 and the marks of those 4 students are 42, 36.5, 39 and 42.5. Find the number of students in the class.
- a)15
- b)20
- c)25
- d)35
Correct answer is option 'B'. Can you explain this answer?
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The average marks of some students in a class is 43. When 4 students ...
Let number of students = x
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43x + (42 + 36.5 + 39 + 42.5) = (x+4) × 42.5
43x + 160 = 42.5x + 170
0.5x = 10
x = 20
Most Upvoted Answer
The average marks of some students in a class is 43. When 4 students ...
The given problem can be solved using the concept of averages. Let's break down the problem step by step to find the number of students in the class.
1. Given Information:
- Average marks of some students in the class is 43.
- When 4 students are included, the average becomes 42.5.
- Marks of the 4 students are 42, 36.5, 39, and 42.5.
2. Average Calculation:
- We know that the average is calculated by summing up all the values and dividing it by the total number of values.
- Let's assume the number of students in the class is 'N'.
- The total sum of marks of all students in the class would be 43 * N.
3. Average Calculation with 4 Students:
- When 4 students are included, the average becomes 42.5.
- The new total sum of marks of all students in the class would be (42.5 * (N + 4)).
- In this case, the sum of marks of the 4 new students would be (42 + 36.5 + 39 + 42.5).
4. Equating Averages:
- Equating the two average calculations, we can write the following equation:
43 * N = (42.5 * (N + 4)) - (42 + 36.5 + 39 + 42.5)
5. Solving the Equation:
- Simplifying the equation, we get:
43N = 42.5N + 170 - 160
- Combining like terms, we get:
0.5N = 10
- Dividing both sides by 0.5, we get:
N = 20
6. Answer:
- Therefore, the number of students in the class is 20.
- Hence, the correct answer is option B.
By following the above steps, we can determine the number of students in the class based on the given information.
1. Given Information:
- Average marks of some students in the class is 43.
- When 4 students are included, the average becomes 42.5.
- Marks of the 4 students are 42, 36.5, 39, and 42.5.
2. Average Calculation:
- We know that the average is calculated by summing up all the values and dividing it by the total number of values.
- Let's assume the number of students in the class is 'N'.
- The total sum of marks of all students in the class would be 43 * N.
3. Average Calculation with 4 Students:
- When 4 students are included, the average becomes 42.5.
- The new total sum of marks of all students in the class would be (42.5 * (N + 4)).
- In this case, the sum of marks of the 4 new students would be (42 + 36.5 + 39 + 42.5).
4. Equating Averages:
- Equating the two average calculations, we can write the following equation:
43 * N = (42.5 * (N + 4)) - (42 + 36.5 + 39 + 42.5)
5. Solving the Equation:
- Simplifying the equation, we get:
43N = 42.5N + 170 - 160
- Combining like terms, we get:
0.5N = 10
- Dividing both sides by 0.5, we get:
N = 20
6. Answer:
- Therefore, the number of students in the class is 20.
- Hence, the correct answer is option B.
By following the above steps, we can determine the number of students in the class based on the given information.
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The average marks of some students in a class is 43. When 4 students are included the average becomes 42.5 and the marks of those 4 students are 42, 36.5, 39 and 42.5. Find the number of students in the class.a)15b)20c)25d)35Correct answer is option 'B'. Can you explain this answer?
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The average marks of some students in a class is 43. When 4 students are included the average becomes 42.5 and the marks of those 4 students are 42, 36.5, 39 and 42.5. Find the number of students in the class.a)15b)20c)25d)35Correct answer is option 'B'. Can you explain this answer?, a detailed solution for The average marks of some students in a class is 43. When 4 students are included the average becomes 42.5 and the marks of those 4 students are 42, 36.5, 39 and 42.5. Find the number of students in the class.a)15b)20c)25d)35Correct answer is option 'B'. Can you explain this answer? has been provided alongside types of The average marks of some students in a class is 43. When 4 students are included the average becomes 42.5 and the marks of those 4 students are 42, 36.5, 39 and 42.5. Find the number of students in the class.a)15b)20c)25d)35Correct answer is option 'B'. Can you explain this answer? theory, EduRev gives you an
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