How Many Seeds a Baby Chicken Needs to Grow Up?

The answer is actually more complicated than you think. According to http://minecraft.gamepedia.com/Chicken , a baby chicken takes 20 mins to grow, and 1 seed can be used to reduce the remaining time by 10%.

So, if 20 mins remaining for the chicken to grow, 1 seed will reduce 10% of that time which is 2 mins. However, 1 seed will reduce just 1 sec if only 10 secs remaining. In other words, no matter how many seeds we use to accelerate the growth, we would still have some time remaining for the chicken to grow.

My question: What mathematical formula can be used to determine the remaining growth time if x seeds are fed to a baby chicken? And how can we use this formula to calculate the number of seeds needed to reduce the growth time to x min?

Feel free to comment with any thoughts you have. If you understand the problem but have no answer, just say "hi".