Multiple choice

The average age of $15 $ students of a class is $15$ years. Out of these, the average age of $5$ students is $14$ years and that of the other nine students is $16$ years. What is the age of the 15th student?

  1. $17$ years
  2. $13$ years
  3. $11$  years
  4. $18$  years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total age of 15 students = 15 * 15 = 225. Age of 5 students = 5 * 14 = 70. Age of 9 students = 9 * 16 = 144. Age of 15th student = 225 - (70 + 144) = 225 - 214 = 11.

AI explanation

The total age of all 15 students is 15 times 15, which equals 225 years. The total age of the first 5 students is 5 times 14, or 70 years, and the total age of the other 9 students is 9 times 16, or 144 years. The combined age of these 14 students is 70 plus 144, giving 214 years. The age of the 15th student is the difference between the total age of all students and the combined age of the 14 students, which is 225 minus 214. The age of the 15th student is 11 years.

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