Yes this approach is correct!!!
1st trans 2 KB, takes 10 ms to receive ack of 2 kB
2nd trans 4 KB, takes 10 ms to receive ack of 4 KB
3rd trans 8 KB, takes 10 ms to receive ack of 8 KB
4th trans 12 KB, takes 10 ms to receive ack of 12 KB
5th trans 14 KB, takes 10 ms to receive ack of 14 KB
6th trans 16 KB, takes 10 ms to receive ack of 16 KB
7th trans 18 KB, takes 10 ms to receive ack of 18 KB
8th trans 20 KB, takes 10 ms to receive ack of 20 KB
9th trans 22 KB, takes 10 ms to receive ack of 22 KB
10th trans 24 KB, takes 10 ms to receive ack of 24 KB
so total 100 ms
hence answer is 100 ms