Question

Hello! I need some reassurance on the top question please

Answer 1

`^7P_4`

Therefore,

`\begin{gathered} nPr=(n!)/(\left(n-r\right)!)=(7!)/(\left(7-4\right)!)=(7!)/(3!)=(7*6*5*4*3!)/(3!)=7*6*5*4=840 \\ \end{gathered}`

Hence, the answer is 840 arrangements.