Dark Skies Observatory is considering several options to purchase a new deep$-$space telescope. Revenue would be generated from the telescope by selling "time and use" slots to various researchers around the world. Four possible telescopes have been identified in addition to the possibility of not buying a telescope if none are financially attractive. The table below details the characteristics of each telescope. An external rate of return analysis is to be performed using a MARR of $25\%.$

$\backslash$table$[[,$T$1,T2,$T$3,$T$4],[$Useful Life,$10$ years,$10$ years,$10$ years,$10$ years$],[$First Cost,$$600,000,$$$800,000,$$$470,000,$$$540,000$

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