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SCORPION-xisa [38]
3 years ago
13

A certain tennis player makes a successful first serve 6969​% of the time. Suppose the tennis player serves 9090 times in a matc

h. ​a)​ What's the mean and standard deviation of the number of good first serves​ expected? ​b) Determine if you can use a normal model to approximate the distribution of the number of good first serves. ​c)​ What's the probability she makes at least 7272 first​ serves?
Mathematics
1 answer:
Wewaii [24]3 years ago
8 0

Answer:

a) 4.387

b) Yes, because np & npq are greater than 10.

c) = 0.017          

Step-by-step explanation:

Give data:

p = 0.69

n = 90

a) a

E(X) = np = 62.1

SD(X) = \sqrt{(np(1-p))}

          =\sqrt{90\times 0.69(1- 0.69)}

          = 4.387

b)

np = 62.1  

q = 1 - p  = 1 - 0.69 = 0.31

npq = 19.251

Yes, because np & npq are greater than 10.

c.

P(X \geq 72   ) = P(X > 71.5) [continuity correction]

=    P(Z> \frac{((71.5-62.1)}{ 4.387})

= P(Z> 2.14 )      

= 1 - P(Z<2.14)              

= 1 - 0.983   (using table)          

= 0.017          

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There are 18 boys and 14 girls (4 more boys than girls.  32 students total.

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Answer:

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Step-by-step explanation:

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3 years ago
Solve the system by substitution:<br> y = -3x + 10<br> y=-3x + 4<br> Please show the steps!
sergiy2304 [10]

Answer:

x=1, y=7

Step-by-step explanation:

y = -3x + 10 - first equation

y=-3x + 4 - second equation

rearrange the expression to

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3x-y= -4

pick an equation and simplify; lets pick the second equation

3x-y= -4

\frac{3x}{3} = \frac{-4+y}{3}  

divide 3 by both sides

x= \frac{-4+y}{3} - third equation

substitute the value of x into an equation; lets pick the first equation

-3x-y= -10

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simplify. -3 cancels 3 so we are left with

-1(-4+y)-y = -10

simplify

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4-2y= -10

subtract 4 from both sides

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divide -2 by both sides

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substitute the value of y, (y=7) in an equation, we are using the second equation

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Marina CMI [18]

Answer:

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Step-by-step explanation:

A simple equation that can be used to figure this out is:

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The variables mean:

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t- total amount of money earned.

(Also, the 1.5 is always used to calculate overtime, no matter what job, unless otherwise specified, and as referred in the problem as "time and a half").

So, to finally work out this problem:

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first, (14*1.5)= $21

($21*63)= $1323.

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3 years ago
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