Question

The speeds in miles per hour of seven randomly selected qualifiers for the Indianapolis 500 (in 2012) are listed below. Estimate the mean qualifying speed with 95confidence. Round your answers to four decimal places.

223.684 222.929 226.240 224.037 226.484 225.172 223.422

Answer 1

To estimate the mean qualifying speed with 95% confidence, we can use the formula for the margin of error. The estimated mean qualifying speed with 95% confidence is between 222.052 and 225.702 miles per hour.

Step-by-step explanation:

To estimate the mean qualifying speed with 95% confidence, we can use the formula for the margin of error:

Margin of Error = Critical Value × Standard Deviation / √n

The critical value for a 95% confidence interval is approximately 1.96. The standard deviation can be calculated by finding the sample mean and subtracting it from each speed, squaring the result, summing all the squared differences, dividing by n-1, and taking the square root. In this case, n is 7. Once we have the margin of error, we can calculate the confidence interval by subtracting the margin of error from the sample mean and adding it to the sample mean.

Once we have all the necessary values, we can substitute them into the formula: Confidence Interval = Sample Mean ± Margin of Error. Rounded to four decimal places, the estimated mean qualifying speed with 95% confidence is between 222.052 and 225.702 miles per hour.

Answer 2

Mean qualifying speed

= 224.5669mi/hr

Speed that passed the average/mean

= 226.240mi/hr ,224.037mi/hr 226.484mi/hr, 225.172 mi/hr

Step-by-step explanation:

Let's understand what mean is then understand what mean qualifying speed is.

First mean is like the average of the seven speed listed below.

So let's find the mean.

Mean = (223.684+ 222.929+ 226.240

+224.037 +226.484+ 225.172

+223.422)/7

Mean = 1571.968/7

Mean = 224.5669

So the mean qualifying speed is those speed that qualifies when the mean is taken, i.e the speed that crossed the average.

Mean qualifying speed are

=226.240 ,224.037,226.484

, 225.172