Answer:
Explanation:
The relation between activity and number of radioactive atom in the sample is as follows 
dN / dt = λ N where λ is disintegration constant and N is number of radioactive atoms 
For the beginning period 
dN₀ / dt = λ N₀
58.2 = λ N₀
similarly 
41 = λ N
dividing 
58.2 / 41 = N₀ / N 
N = N₀ x .70446
formula of radioactive decay 


- λ t = ln .70446 =   - .35 
t = .35 / λ
λ = .693 / half life 
= .693 / 5715 
= .00012126
t = .35 / .00012126
= 2886.36 
= 2900 years ( rounding it in two significant figures ) 
 
        
             
        
        
        
Answer:
R = 6.8
Explanation:
Given data:
Richter scale
where R - magnitude of earthquake of Richter scale
I - quake's intensity 
 - minimum intensity earthquake
 - minimum intensity earthquake
Plugging all information in the equation to get Richter's scale


R = 6.8
 
        
             
        
        
        
Answer: Different types of telescopes usually don't take simultaneous readings. Space is a dynamic system, so an image taken at one time is not necessarily the precise equivalent of an image of the same phenomena taken at a later time. And often, there is barely enough time for one kind of telescope to observe extremely short-lived phenomena like gamma-ray bursts. By the time other telescopes point to the object, it has grown too faint to be detected.
Explanation: Trust me