Question $11$

Your neighbour goes to the post office once a month and picks up two cheques, one for $18,000$ and one for $4,000.$ The larger cheque takes $4$ days to clear after it is deposited; the smaller one takes $6$ days. Assume $30$ days per month. What is the weighted average delay?

$4\mathrm{.}36$ days

$4\mathrm{.}78$ days

$5\mathrm{.}00$ days

$4\mathrm{.}21$ days