Multiple choice

In a school, the average salary of all employees including teacher sand helpers is Rs. 15000. The average salary of teachers is Rs. 20000, while average salary of all helpers is Rs. 9000. Find the number of helpers in the school, if there are 12 teachers.

  1. 11

  2. 13

  3. 10

  4. 12
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The teachers earn 12 x Rs. 20000 = Rs. 240000. If there are h helpers, then 15000(12 + h) = 240000 + 9000h, which gives h = 10.

AI explanation

Using the method of alligation, the overall average salary is Rs. 15000, the teachers' average is Rs. 20000, and the helpers' average is Rs. 9000. The difference between the teachers' average and the overall average is Rs. 5000, and the difference between the overall average and the helpers' average is Rs. 6000. This establishes a ratio of teachers to helpers of 6000 to 5000, or 6:5. Since there are 12 teachers representing 6 parts, each part equals 2 people; therefore, the 5 parts representing helpers equals 10 helpers.

Keep practicing — related questions