Multiple choice

The average age of a teacher and three students is 20 years. If all the three students are of same age and the difference between the age of the teacher and each student is 20 years, then what is the age of the teacher?

  1. 25 years

  2. 30 years

  3. 35 years

  4. 45 years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let student age be x. Teacher age is x + 20. Average = (x + 20 + 3x) / 4 = 20. Thus, 4x + 20 = 80, 4x = 60, x = 15. Teacher age = 15 + 20 = 35.

AI explanation

Let the age of each student be S and the age of the teacher be T, establishing the equations T + 3S = 80 and T - S = 20. Multiply the second equation by 3 to get 3T - 3S = 60. Adding this to the first equation eliminates S, yielding 4T = 140. Solving for T gives the teacher's age as 35 years.

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