Answer:
88.5
Step-by-step explanation:
(90+82+81+2x)/5=86
90+82+81+2x=430
2x=177
x=88.5
Answer:6018
Step-by-step explanation:
Given Sequence

It represent an A.P. with
first term 
common difference 
So sum of 51 term
![S_n=\frac{n}{2}[2a+(n-1)d]](https://tex.z-dn.net/?f=S_n%3D%5Cfrac%7Bn%7D%7B2%7D%5B2a%2B%28n-1%29d%5D)
![S_{51}=\frac{51}{2}\times [2\times (-282)+(51-1)16]](https://tex.z-dn.net/?f=S_%7B51%7D%3D%5Cfrac%7B51%7D%7B2%7D%5Ctimes%20%5B2%5Ctimes%20%28-282%29%2B%2851-1%2916%5D)
![S_{51}=\frac{51}{2}\times [-564+800]](https://tex.z-dn.net/?f=S_%7B51%7D%3D%5Cfrac%7B51%7D%7B2%7D%5Ctimes%20%5B-564%2B800%5D)
![S_{51}=\frac{51}{2}\times [236]](https://tex.z-dn.net/?f=S_%7B51%7D%3D%5Cfrac%7B51%7D%7B2%7D%5Ctimes%20%5B236%5D)


The final probability is the weighted average of the playing probabilities calculated over the possible weather options:
P(john practices cello; given that it rains) * P(it rains) +
P(john practices cello; given that it does not rain) * P(it does not rain) =
0.6 * 0.7 + 0.4 * 0.3 = 0.54
The probability is 54%