At a certain temperature 6% molecules of a gas have speed `2 m//s`, 9% have speed `3 m//s`, 30% have speed `9 m//s`, 28% have speed `11 m//s`, 20% have speed `13 m//s` and 7% have speed `18 m//s`. Calculate `U_(mp), U_(av)` and `U_(rms)` at that temperature.

Explanation

To solve the problem, we need to calculate the most probable speed (U_mp), average speed (U_av), and root mean square speed (U_rms) of the gas molecules based on the given data.

### Step-by-Step Solution

1. **Identify the most probable speed (U_mp)**:
- The most probable speed is defined as the speed at which the maximum number of molecules is found.
- From the given data, we see that 30% of the molecules have a speed of 9 m/s, which is the highest percentage.
- Therefore, the most probable speed (U_mp) is:
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