Multiple choice

The mean weight of a class of $34$ students is $6.5$kg. If the weight of the teacher is included, the mean rises by $500$g. Then the weight of the teacher is __________.

  1. $175$kg
  2. $62$kg
  3. $64$kg
  4. $72$kg
Reveal answer Fill a bubble to check yourself
C Correct answer
AI explanation

Using the direct mean formula, the total weight of 34 students is 34 multiplied by 6.5 kg, which equals 221 kg. The new mean is 6.5 kg plus 0.5 kg, making it 7 kg, so the total weight of 35 people becomes 35 multiplied by 7 kg, equaling 245 kg. The teacher's weight is the new total minus the old total: 245 kg minus 221 kg equals 64 kg.