In 2 minutes the number of words typed by Gopal & Madhava = 30 + 25 = 55
Hence, in 10 pair of minutes the number of words typed by both = 55 × 10 = 550
Then, in 21th minute Gopal will type 30 words.
The number of words typed in 21 minutes = 550 + 30 = 580
Remaining number of words = 600 – 580 = 20 words
Which can be typed by Madhava in 22th minutes
Now, 25 words typed in 1 minute
Hence, 20 words will be typed in
×20 min =
×60 sec = 48 sec.
Therefore, total time taken = 21 min 48 sec.