A group of seven galaxies each of a total mass$\mathrm{<font><font>1</font></font>}\mathrm{<font><font>0</font></font>}\mathrm{<font><font>1</font></font>}\mathrm{<font><font>2</font></font>}$ M form a stable cluster in a sphere of constant radius $\mathrm{<font><font>1</font></font>}\mathrm{<font><font>.</font></font>}\mathrm{<font><font>5</font></font>}$Mpc$<font><font>.</font></font>$ At what redshift did this group have the same mean density as the surrounding Universe? You may assume that the Universe is flat with $$M$<font><font>=</font></font>\mathrm{<font><font>1</font></font>}<font><font>,</font></font>$and that the Hubble constant is H$\mathrm{<font><font>0</font></font>}<font><font>=</font></font>\mathrm{<font><font>7</font></font>}\mathrm{<font><font>0</font></font>}$km s$\mathrm{<font><font>1</font></font>}$Mpc$\mathrm{<font><font>1</font></font>}$ $<font><font>.</font></font>$

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To determine the redshift at which the group of galaxies had the same mean density as t... View the full answer