Home/ Questions/Q 1945
In Process

selectionway.org Latest Questions

Content Team
  • 0
  • 0
Asked: 2026-03-25T15:35:18+00:00

The average of 12 numbers is 48. The average of the first 5 numbers is 45, and the average of the next 4 numbers is 52. If the 10th number is 10 less than the 11th number and is 5 more than the 12th number, then the average of the 11th and 12th numbers is:

  • 0
  • 0
  1. 50.5
  2. 46.5
  3. 47.5
  4. 48.5
Share
Leave an answer

Leave an answer

Browse

1 Answer

  1. Content Team
    This answer was edited.

    Given:

    Average of 12 numbers = 48

    Average of first 5 numbers = 45

    Average of next 4 numbers = 52

    10th number = 11th number – 10

    10th number = 12th number + 5

    Formula used:

    Sum = Average × Number of terms

    Calculations:

    Total sum of 12 numbers = 48 × 12 = 576

    Sum of first 5 numbers = 45 × 5 = 225

    Sum of next 4 numbers = 52 × 4 = 208

    Sum of 10th, 11th, and 12th numbers = 576 – (225 + 208) = 143

    Let the 11th number = x.

    Then, 10th number = x – 10 and 12th number = x – 15.

    Sum of 10th, 11th, and 12th numbers:

    (x – 10) + x + (x – 15) = 143

    ⇒ 3x – 25 = 143

    ⇒ 3x = 168

    ⇒ x = 56

    11th number = 56

    12th number = 56 – 15 = 41

    Average of 11th and 12th numbers = (56 + 41) ÷ 2 = 48.5

    ∴ The average of the 11th and 12th numbers is 48.5.