Jack invests $1,000$ at the end of each year for $n$ years at an effective interest rate of $i.$ At the end of $n$ years, it has accumulated to $x.$

Jill invests $2,000$ at the end of each year for $2n$ years at an effective interest rate of $i.$ At the end of $2n$ years, it has accumulated to $6x.$

Junior invests $3,000$ at the end of each year for $3n$ years at an effective interest rate of $i.$ At the end of $3n$ years, it has accumulated

to $Y.$

$i>0.$ Calculate $Y.$

$17x$

$18x$

$19x$

$20x$

$21x$