Question

Here is a summary of the Boston Marathon completion times for two years.

Answer 1

Answer:

"It's approximately normal, because both sample sizes are at least 30."

Step-by-step explanation:

The shape of the population distribution is unknown; however as the sample size is 35 (fulfills the sample size criteria: $\geq$ 30), we can conclude that the sampling distribution is therefore approximately normal.

Answer 2

Answer:

Here is a summary of the Boston Marathon completion times for two years.

Year

Mean (minutes)

Standard deviation (minutes)

Number of runners

2012

263

50

21,576

31,984

2014

243

52

A sports journalist takes separate random samples of 35 runners from each year. Then they look at the

difference in the mean completion time sampled from each year 2012 - 2014).

What do we know about the shape of the sampling distribution of D2012 22014, and why?Step-by-step explanation: