Multiple choice

The average age of 40 student of a class is 18 yr. when 20 new students are admitted to the same class, the average age of the students of the class is increased by 6 months. The average age of newly admitted students is

  1. 19yr

  2. 19yr 6 months

  3. 20 yr

  4. 20 yr 6 months
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Initial sum = 40 * 18 = 720. New total students = 60. New average = 18.5. New sum = 60 * 18.5 = 1110. Sum of 20 new students = 1110 - 720 = 390. Average of new students = 390 / 20 = 19.5 years = 19 years 6 months.

AI explanation

Using the average formula, the total age of the initial 40 students is 40 multiplied by 18, which equals 720 years. The new average for the 60 students becomes 18.5 years, making their total age 60 multiplied by 18.5, or 1110 years. The total age of the 20 newly admitted students is 1110 minus 720, equaling 390 years, so their average age is 390 divided by 20, which results in 19 years and 6 months.

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