Answer:
the answer is 9 please I hope i get it right
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Answer:
He needs 7 more consecutive successful first serves to raise his first serve percentage to 60%.
Step-by-step explanation:
After n consecutive serves, his total number of serves is going to be n+8, since he has already served 8 times. In the best case, his number of successful first serves is n+2.
His percentage of succesful first serves is the division of the number of succesful first serves divided by the total number of serves. So
![P = \frac{n+2}{n+8}](https://tex.z-dn.net/?f=P%20%3D%20%5Cfrac%7Bn%2B2%7D%7Bn%2B8%7D)
We want
. So
![0.6 = \frac{n+2}{n+8}](https://tex.z-dn.net/?f=0.6%20%3D%20%5Cfrac%7Bn%2B2%7D%7Bn%2B8%7D)
![n+2 = 0.6*(n+8)](https://tex.z-dn.net/?f=n%2B2%20%3D%200.6%2A%28n%2B8%29)
![n + 2 = 0.6n + 4.8](https://tex.z-dn.net/?f=n%20%2B%202%20%3D%200.6n%20%2B%204.8)
![n - 0.6n = 4.8 - 2](https://tex.z-dn.net/?f=n%20-%200.6n%20%3D%204.8%20-%202)
![0.4n = 2.8](https://tex.z-dn.net/?f=0.4n%20%3D%202.8)
![n = \frac{2.8}{0.4}](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7B2.8%7D%7B0.4%7D)
![n = 7](https://tex.z-dn.net/?f=n%20%3D%207)
He needs 7 more consecutive successful first serves to raise his first serve percentage to 60%.
35%
---- Than cross multiply with ---- = 24500
100% 100 --------
100
Which ends up to be 245.