A store has recorded the last four orders of boxes of pens as follows $($where a box is the 'unit'$)$:

Order Units Cost per Total Cost

Ordered unit $ of order

$12010\mathrm{.}00$ $$200\mathrm{.}00$

$2408\mathrm{.}00$ $$320\mathrm{.}00$

$3407\mathrm{.}00$ $$280\mathrm{.}00$

$41004\mathrm{.}00$ $$400\mathrm{.}00$

Total

What is the weighted average cost for ordering a box of pens?

Question $8$Select one:

a$.$

$1200$

b$.$

$4\mathrm{.}00$

c$.$

$200$

d$.$

$6\mathrm{.}00$

e$.$

$10\mathrm{.}00$