3.3 % chance that will randomly pick tallest
![C(n,n)=\dfrac{n!}{n!(n-n)!}=\dfrac1{0!}=\dfrac11=1](https://tex.z-dn.net/?f=C%28n%2Cn%29%3D%5Cdfrac%7Bn%21%7D%7Bn%21%28n-n%29%21%7D%3D%5Cdfrac1%7B0%21%7D%3D%5Cdfrac11%3D1)
In other words, how many ways are there to choose
![n](https://tex.z-dn.net/?f=n)
objects from a total of
![n](https://tex.z-dn.net/?f=n)
objects? Just one; take all of them at the same time.
First term [ a ] = 6.3
Common difference [ d ] = 8.8 - 6.3 = 2.5
Using general term formula,
![t_{n} = a + (n-1)d](https://tex.z-dn.net/?f=t_%7Bn%7D%20%3D%20a%20%2B%20%28n-1%29d)
78.8 = 6.3 + (n-1)*2.5
2.5*(n-1) = 72.5 [ Dividing both sides by 2.5 ]
n-1 = 29
n = 30
Hence, 78.8 is the
30th term in the arithmetic series.
2x+7=x+3
2x+7=3
-×
x+7=3
-7 -7
x=-4