Reading Comprehension
Directions
In this section you will read several passages. Each 1 is followed by several questions. You are to choose the 1 best answer to each question.
Answer all questions about the information in a passage on the basis of what is stated or implied in that passage.
Passage
A new atomic clock being developed for navigation satellites will perform better than previous devices. The clock will use a new microwave cavity design to provide a compact and lightweight package and new electronic techniques to maintain long-term stability. The clock can provide precise navigation information because it is stable to one second in three million years. The differences in the time when signals from four satellites arrive at one location can be used to calculate that position to within a few yards.
Practice Questions 6–8
According to the passage, signals from how many satellites will be used to calculate a position?