Examples: 


  "One car was parked outside of the gate." 
  "Your work volume is increased or not"
  "He was arrested"
  "She was raped"
  "After accident he was taken to hospital"
  "He was informed about this"
  “My heart was broken”


All above statements can be in the stative form if we do not mentioned the agent.
But if we use the agent i.e. By Driver, By Boss,  By Police, By  boyfriend, By  friend, By  father, By  husband respectively, then sentence become as passive voice.

My questions are 
a) How to quickly make out whether a sentence is in the passive voice or just a simple sentence (Stative)?

B) If i use had been in above sentence does it mean the same?


Question: How to calculate mean and standard deviation in R given confidence interval and a normal or gamma distribution?
Answer: If you mean the true parameters of course the answer is no.  But if you mean that you want to recover the sample estimates from the confidence interval the answer is yes for the normal distribution if the sample size $n$ is also given.

If the confidence interval was $(1,6)$, then $1= \overline{X}-1.96 \cdot S/\sqrt{n}$ and $6=\overline{X}+1.96 \cdot S/\sqrt{n}$.  So $\overline{X}= (6+1)/2=3.5$
and then $6=3.5 +1.96 \cdot S/\sqrt{n}$ or $S=\sqrt{n} 2.5/(1.96)$.

For the gamma distribution this paper shows various ways to get the approximate and exact confidence intervals for rates.  Getting the parameter estimates from these confidence intervals may be complicated.