The average age of class of 50 students is 24 years. If the average of 10 of them is 22 years, while average of another 10 is 26 years. What is the average of the remaining 30 students?
- Difference Total
50 Students
(22 Years) - 2 =>
10 (26 Years) + 2 =>
30(?) -20
+20
Observe that 10 students have an average of 22 years (2 years below 24). While another 10 students
have an average of 26 years (2 years above 24). Thus, the effect by (-2) is nullified by the effect of
(+2).As such, the average of remaining 30 students would remain same as 24 years.
Let the average age of the remaining 30 students be x.
We know that the average age of the entire class of 50 students is 24 years. Therefore, the total age of all the students is:
50 * 24 = 1200 years
We also know that the average age of 10 of the students is 22 years. Therefore, the total age of these 10 students is:
10 * 22 = 220 years
Similarly, the total age of the other 10 students whose average age is 26 years is:
10 * 26 = 260 years
Now, let's use the formula for the average:
Average = (Sum of values) / (Number of values)
We can use this formula to find the total age of the remaining 30 students:
Total age of remaining 30 students = (50 * 24) - 220 - 260
Total age of remaining 30 students = 1200 - 480
Total age of remaining 30 students = 720
Therefore, the average age of the remaining 30 students is:
Average age of remaining 30 students = Total age of remaining 30 students / Number of remaining students
Average age of remaining 30 students = 720 / 30
Average age of remaining 30 students = 24
Hence, the correct answer is option B, which is 24 years.
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