P. 229 Strengthen question

[emilyyingxiong]

Although I got the question right by choosing E, but there is some doubt about choice C.

C. "No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board'


I understand there is two "no", does that mean there is problem with electronic devices?
Since double negative equals one positive?
But the explanation says "show that when the cause does not occur, the effect does not occur."


Confused.
Could some expert please explain?

[Nikki Siclunov]

Hi emilyyingxiong,

Let's take a moment to understand precisely what answer choice (C) means:

No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board

In other words, when the flight has no passengers with electronic devices on board, there were no problems with the navigational equipment. While this doesn't prove that the electronic devices put navigational systems at risk, it shows that where the purported cause is absent (no electronic devices), the undesirable effect is also absent (no navigational malfunctions). This strengthens the causal relationship in the conclusion, making answer choice (C) incorrect.

Hope this helps!

[emilyyingxiong]

Thank you Nikki~~~~~
<3