Atennis player keeps track of the number of successful first serves he makes. during the first 8 service points of a game, only 2 of his first serves are playable, so his first serve percentage is 25%. how many more consecutive successful first serves must he have to raise his first serve percentage to 60%?

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

We want . So

He needs 7 more consecutive successful first serves to raise his first serve percentage to 60%.

answer:  

123455421

step-by-step explanation: easy

answer: .64

step-by-step explanation

set up the formula for standard deviation for this set of numbers, then simplify