Multiple choice

The average weight of a class of 35 students is 47.5 kg. If the weight of the teacher is included, the average rises by 500 g. The weight of the teacher is

  1. 65.5 kg

  2. 66.5 kg

  3. 48 kg

  4. 47 kg
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A Correct answer
Explanation

The total weight of 35 students is 35 * 47.5 = 1662.5 kg. With the teacher, there are 36 people and the average is 48 kg. Total weight = 36 * 48 = 1728 kg. The teacher's weight = 1728 - 1662.5 = 65.5 kg.

AI explanation

Using the basic average formula, the total weight of the 35 students is 35 times 47.5 kg, which equals 1662.5 kg. When the teacher is included, the new average is 48 kg for 36 people, making the new total weight 36 times 48, which equals 1728 kg. The difference between the new total weight and the old total weight gives the teacher's weight, so 1728 minus 1662.5 equals 65.5 kg.

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