How many different arrangements can be made using the letters of the word MEADOWS such that all vowels are positioned only in the even-numbered slots?

Explanation

The word MEADOWS consists of 7 letters, including 3 vowels (E, A, O). The vowels must occupy the even positions (2nd, 4th, and 6th), which gives 3 positions for 3 vowels. These vowels can be arranged among themselves in 3! = 6 ways. The remaining 4 consonants can be arranged in the 4 odd positions in 4! = 24 ways. Therefore, the total number of arrangements is 6 × 24 = 144.