Answer i dont even know im just putting this cus id ont care
Explanation:
 
        
             
        
        
        
There was a supercontinent called Pangea
        
             
        
        
        
Well, the thing is: we don't really know, as we don't even know how many species there are on earth. 
If we take a look at the estimates of <span>World Wide Fund for Nature, an organization that works toward combating species extinction, their estimates vary from 200 to 100 000 - but a probable number is 20 000 (d). </span>
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Answer:
Time take to fill the standing wave to the entire length of the string is 1.3 sec.
Explanation:
Given : 
The length of the one end  
  , frequency of the wave
, frequency of the wave  = 2.3 Hz, wavelength of the wave λ = 1 m.
 = 2.3 Hz, wavelength of the wave λ = 1 m.
Standing wave is the example of the transverse wave, standing wave doesn't transfer energy in a medium.
We know,
∴  λ
λ 
Where  speed of the standing wave.
 speed of the standing wave.
also, ∴ 
where  time take to fill entire length of the string.
 time take to fill entire length of the string. 
Compare above both equation,
⇒    
  sec
 sec
      
Therefore, the time taken to fill entire length 0f the string is 1.3 sec.