Answer:
Pi(3.14) radians or 180º degrees
Explanation:
First of all, we need to obtain the wavelength of a wave traveling to the speed of sound and 420 Hz of frequency.
The formula is:

where l = wavelength in meters
With current values:
l = 336 [m/s]/420[1/s] = 0.8 meters
Since a complete cycle (360º or 2pi radians) needs 0.8 meters to complete, 0.4 meters or 40 cm is just half of it, making a 180º degree phase or 3.14 radians.
Density =mass/volume 120/200 =0.6 g/cm
Yes,Physics 5pts just now<span>are the 5 steps in the process of air circulation in order</span>
When you put that into a Punnett square you first use the FOIL method because this is a dihybrid case where two traits are considered. This will be the resulting Punnett square:
PL Pl pL pl
PL PPLL PPLl PpLL PpLl
Pl PPLl PPll PpLl Ppll
pL PpLL PpLl ppLL ppLl
pl PpLl Ppll ppLl ppll
Now based on the Punnett square above, you can get the ratio. Remember that the dominant trait will always be expressed when you count phenotype combinations so as long as there is a capital letter in the combination, it will always be the one expressed.
So there are 9 polka dot, long eyelashes(PL), 3 polka dot, short eyelashes (Pl), 3 solid color, long eyelashes (pL), 1 solid short eyelashes(pl).
So your answer is D. 9:3:3:1 ratio
I think it would be at 3 or 6 but I would go with 3 not really sure tho