2022 · Q109
If the average of the first four of five numbers in decreasing order is 25 and the average of the last four numbers is 20, then what is the difference between the first and the last number?
general-mental-abilityquantitative-aptitude
- A5
- B10
- C15
- D20
Explanation
Let the numbers in decreasing order be a > b > c > d > e. The first four average 25, so a + b + c + d = 100; the last four average 20, so b + c + d + e = 80. Subtracting the second sum from the first gives a − e = 20, which is the difference between the first and the last number.