In a book store, each of the word of the glowsign board “MODERN BOOK STORES” is visible after $5/2, 17/4$ and $41/8$ seconds respectively. Each of them is put off for $1$ second. Find the time after which one person can see a completely visible glowsign board.
- $73.5$ seconds
- $79.4$ seconds
- $68.2$ seconds
- None of these