9 times
Explanations:[tex]\text{Half life of Helium-5 = 7.6 }\times10^{-22}\text{ seconds}[/tex][tex]\text{Half life of Helium-9 = 7 x 10}^{-21}\text{ seconds }[/tex]The number of times that the half life of Helium-9 is greater than that of Helium-5 is calculated as:
[tex]\begin{gathered} \frac{\text{ 7 x 10}^{-21}}{\text{ 7.6 }\times10^{-22}} \\ 0.92\text{ }\times\text{ 10 }=\text{ 9}.2 \end{gathered}[/tex]9.2 can be approximated to 9
Therefore, the half life of Helium-9 is 9 times greater than the half life of Helium-5
