A Tennis Player Usually Makes a Successful First Serve 74

question 160

Multiple Choice

A tennis player usually makes a successful first serve 74% of the time.She buys a new racket hoping that it will improve her success rate.During the first month of playing with her new racket she makes 402 successful first serves out of 500.Is this evidence that with the new racket her success rate has improved? In other words,is this an unusual result for her? Explain.

• A)No; we would normally expect her to make 370 first serves with a standard deviation of 19.24.402 is 1.7 standard deviations above the expected value.That's not an unusual result.
• B)No; we would normally expect her to make 370 first serves with a standard deviation of 96.20.402 is 0.3 standard deviations above the expected value.That's not an unusual result.
• C)No; we would normally expect her to make 370 first serves with a standard deviation of 9.81.402 is 3.3 standard deviations above the expected value.That's not an unusual result.
• D)Yes; we would normally expect her to make 370 first serves with a standard deviation of 96.20.402 is 0.3 standard deviations above the expected value.That's an unusual result.
• E)Yes; we would normally expect her to make 370 first serves with a standard deviation of 9.81.402 is 3.3 standard deviations above the expected value.That's an unusual result.

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