The mu mesons generated by cosmic rays just outside Earth’s atmosphere travel to Earth at speeds approaching the speed of light.
Facts
contrast Mm's generated by cosmic rays just outside Earth’s atmosphere travel at speeds approaching the speed of light, whereas mm's in the lab are nearly at rest.
math-y contrast lab-mm to decay < space mm to reach detection TIME
conditional + implicit fact that triggers contrapositive If mm's traveling through the atmosphere at speeds approaching the speed of light typically decay as fast as lab-mm's, then we should detect only about one one-hundredth of the number we actually do detect.
Evaluate
We know that space Mm's are fast (near speed of light) while lab Mm's are slow (nearly at rest).
And we know that lab Mm's decay in less time than it takes for a space Mm to be detected on Earth.
Is there anything we can get by combining those ideas? Nothing obvious.
Meanwhile, the final sentence gives us a conditional statement as well as an implicit fact that triggers that conditional idea. That sounds fancy, but it just means that the sentence with the rule is also triggering its own contrapositive.
Suppose you heard, What can you infer? Diana is not a good dancer.
The sentence conveys that Diana has not placed as high as would be required for a good dancer, so we can apply the rule to her and derive that she's not a good dancer.
Similarly,
This statement is already telling us that the necessary condition—the "then" part—is not true. We are not detecting one one-hundredth of the number we actually do detect. We are detecting the number that we actually do detect.
So this allows us to infer that
Goal
If we can look past the scientific terms and get a handle on the essence of what these statements are telling us, we can make a very good prediction. We expect a correct answer to indicate that MMs traveling through the atmosphere decay more slowly that ones created in the lab.