Chapter 26, Problem 8P

To determine

The speed of a ${\sum }^{+}$ particle with respect to a laboratory observer using the life-time of the particle in its own frame (from the problem 7 of chapter 26) to be equal to $0.80\times {10}^{-10}\text{ s}$ and the life-time of the particle with respect to the laboratory observer to be equal to $1.0\times {10}^{-10}\text{ s}$.