Expedia would like to test the hypothesis that the average roundtrip airfare between philadelphia and paris is higher for a flight originating in philadelphia when compared to a flight originating in paris. the following data summarizes the sample statistics for roundtrip flights originating in both cities. assume that the population variances are known. if population 1 is defined as flights originating in philadelphia and population 2 is defined as flights originating in paris, the 90% confidence interval for the difference in population means is

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.

Which diagram shows lines that must be parallel lines cut by transversal?