The Cougar Swim Club acquired some Speedo Fastskin bodysuits and decided to test them out. A number of the club's fastest swimmers performed a 50m freestyle swim in a regular spandex bodysuit and in a Speedo Fastskin suit. The table below summarizes their times in seconds. Swimmer SpandexSpeedo Fastskin1 31.1 29.12 28.9 30.43 31.4 32.04 34.9 31.75 27.7 28.26 36.7 32.97 33.3 28.68 30.8 26.2Perform a t-test for dependent means to determine if there is a difference between the regular spandex suit and the Fastskin bodysuit in terms of performance. t = df = Critical value of t = (use alpha = 0.05)Would you reject the null hypothesis?

T = 2.215

df = 7

Critical value = 2.364

Fail to reject the null

Step-by-step explanation:

Swimmer __Spandex __Speedo Fastskin__ d

1 31.1 29.1 __ 2

2 28.9 30.4 __ -1.5

3 31.4 32.0 __ - 0.6

4 34.9 31.7 __ 3.2

5 27.7 28.2 __ - 0.5

6 36.7 32.9 ___ 3.8

7 33.3 28.6 ___ 4.7

8 30.8 26.2 ___ 4.6

The mean difference = Σd / n

2, - 1.5, - 0.6, 3.2, - 0.5, 3.8, 4.7, 4.6

μd = Σd / n = 15.7 / 8 = 1.9625

Sd = standard deviation of difference = 2.5065 (using calculator)

H0 : μd = 0

H1 : μd ≠ 0

The test statistic:

T = μd / (Sd/√n)

T = 1.9625 / (2.5065/√8)

T = 2.2145574

The degree of freedom, df = n - 1 = 8 - 1 = 7

Using a Pvalue calculator :

α = 0.05

Critical value, Tcritical = 2.364 (T distribution table)

Since Test statistic < Critical value

we fail to reject H0 ;

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