Multiple choice

The average weight of 29 students is 28 kg. By the admission of a new student the average weight is reduced to 27.8 kg. The weight of the new student is

  1. 22 kg

  2. 21 kg

  3. 22.4 kg

  4. 21.6 kg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total weight of 29 students = 29 * 28 = 812. Total weight of 30 students = 30 * 27.8 = 834. New student = 834 - 812 = 22 kg.

AI explanation

The total weight of the initial 29 students is 29 multiplied by 28, which equals 812 kg. The total weight of all 30 students with the new average is 30 multiplied by 27.8, which equals 834 kg. The difference between these totals is negative 22 kg; the calculation shows the initial total weight should have been higher, but working backward from the provided options, the new student's weight is 22 kg.

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