3.1. A transgalactic ship has encountered an amazing meteorite stream. Some of the meteorites are flying along a straight line, one after another, at equal speeds and at equal distances from each other. Another part is flying the same way but along another straight line parallel to the first, at the same speeds but in the opposite direction, and at the same distance from each other. The ship is flying parallel to these lines. Astronaut Gavrila noted that the ship meets meteorites flying towards the ship every 7 s, and meteorites flying in the same direction as the ship every 13 s. He wondered how often meteorites would fly past him if the ship were to stand still. It seemed to him that he should take the arithmetic mean of the two given times. Is Gavrila right? If yes, write down this arithmetic mean in the answer. If not, specify the correct time in seconds, rounded to tenths.
3.1. A transgalactic ship has encountered an amazing meteor shower. Some of the meteors are flying along a straight line, one after another, at the same speeds and at equal distances from each other. Another part is flying in the same way but along another straight line parallel to the first, at the same speeds but in the opposite direction, and at the same distance from each other. The ship is flying parallel to these lines. Astronaut Gavrila recorded that the ship meets meteors flying towards the ship every 7 s, and meteors flying in the same direction as the ship every 13 s. He wondered how often meteors would fly past him if the ship were to stand still. It seemed to him that he should take the arithmetic mean of the two given times. Is Gavrila right? If yes, write down this arithmetic mean in the answer. If not, specify the correct time in seconds, rounded to tenths.

Answer. $\{9.1\}$.