Question

It is believed that using a solid state drive (SSD) in a computer results in faster boot times when compared to a computer with a traditional hard disk (HDD). You sample 14 computers with an HDD and note a sample average of 28.763 seconds with a standard deviation of 4.2842 seconds. A sample of 11 computers with an SSD show an average of 8.298 seconds with a standard deviation of 2.1562 seconds. Construct a 90% confidence interval for the difference between the true average boot times of the two types of hard drives. Assume the difference will represent (HDD-SSD) and that the population standard deviations are statistically the same.

Question 8 options:

1)	(19.046, 21.884)

2)	(18.034, 22.896)

3)	We only have the sample means, we need to know the population means in order to calculate a confidence interval.

4)	(18.132, 22.798)

5)	(11.905, 29.025)

Answer 1

Given that,

For HDD :

For SSD :

Since, population standard deviations are statistically the same, we used pooled standard deviation.

Using TI-83 plus calculator we get, the 90% confidence interval for the difference between the true average boot times of the two types of hard drives is, (18.034, 22.896)