|13-6| < x < |13+6|
So the range will be:
7 < x < 19
There are 
ways of picking 2 of the 10 available positions for a 0. 8 positions remain.
There are 
ways of picking 3 of the 8 available positions for a 1. 5 positions remain, but we're filling all of them with 2s, and there's 
way of doing that.
So we have
The last expression has a more compact form in terms of the so-called multinomial coefficient,
Answer: 17/20
<u>Divide</u>
34/40 ÷ 2/2 = 17/20
Divide each side by 2 so it'll be 2/2.
At starting hot-air balloon starts 6 feet.
So, at t = 0 , h = 6 feet.
Now, distance travelled per minute is 20 feet.
So, extra distance travelled in t minutes is 20t feet.
Now,
Total height = Staring height + increase in height w.r.t time.
h = 6 + 20t
Therefore, the height h in feet as a function of time t in minutes is h = 6 + 20t .
Hence, this is the required solution.
