Final Answer:
1. The mean of the paired differences
is
, and the standard deviation
is
. 2. The 90% confidence interval for the true difference between population means is

Step-by-step explanation:
To find the mean of the paired differences
, subtract each corresponding pair of entries from Population 1 and Population 2, then calculate the average. In this case,

The critical value is obtained from a t-distribution table for a 90% confidence interval with degrees of freedom equal to the sample size minus one. For a two-tailed test, the critical value is

The standard deviation of the paired differences
is calculated based on the differences between each pair and the mean of the paired differences. In this scenario,

The confidence interval is constructed using the formula
, where
is the critical value,
is the standard deviation of the paired differences, and
is the sample size. Plugging in the values, we get a 90% confidence interval of
for the true difference between the population means.