Multiple choice

The average age of $14$ girls in a class is $20$ years and of $18$ boys is $23$ years. Find average age of class.

  1. $21\, \frac{11}{16}$ years
  2. $21\, \frac{9}{16}$ years
  3. $21\, \frac{7}{16}$ years
  4. $21\, \frac{13}{16}$ years
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A Correct answer
Explanation

Total age of girls = 14 * 20 = 280. Total age of boys = 18 * 23 = 414. Total age = 694. Total students = 32. Average = 694 / 32 = 347 / 16 = 21 and 11/16.

AI explanation

The total age of the 14 girls is 14 times 20, which is 280 years, and the total age of the 18 boys is 18 times 23, which is 414 years. The sum of the ages of all 32 students in the class is 280 plus 414, giving 694 years. Using the basic average formula, the class average is 694 divided by 32, which equals 21 and 22/32, simplifying to 21 and 11/16 years.

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