Multiple choice

There are $30$ boys and $40$ girls in a class. If the average age of boys is $10$ yr and average age of girls is $8$ yr, then the average age of the whole class is

  1. $8\ year$
  2. $8.86\ year$
  3. $8.2\ year$
  4. $9\ year$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total age = (30 * 10) + (40 * 8) = 300 + 320 = 620. Total students = 30 + 40 = 70. Average = 620 / 70 = 62 / 7 = 8.857... which rounds to 8.86.

AI explanation

The total age of the 30 boys is 30 times 10, which equals 300 years, and the total age of the 40 girls is 40 times 8, which equals 320 years. The combined total age for the whole class of 70 students is 300 plus 320, yielding 620 years. Dividing this total by 70 gives the average age of the whole class as 8.86 years.

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