The first thing you need to do, is to find the half life which is ( = (ln2)/k). To find it, we have to use
the rate constant k
The first order reaction has to be like this :
![ln[A] = ln[A]o -kt at time t= 62 min](https://img.qammunity.org/2017/formulas/chemistry/high-school/srt9ahgl2fmg7lou3d19qwuui4giuhzefw.png)
Then :
![[A] = 67% [A]o or 0.67[A]o](https://img.qammunity.org/2017/formulas/chemistry/high-school/td7pt02qb0yf8i719te1120a7tnwuejjzg.png)
Then substitute these value and kind the k value.
After substitution you can easily find what you were asked to find.