The following information pertains to the physical inventory of Electronics Unlimited taken at December $31$ :

$\backslash$table$[[,,$Per Unit$],[$Product$,\backslash$table$[[$Units on$],[$Hand$]],$Cost,NRV$,],[$Audio equipment:,,,,$],[$Wireless audio receivers,$339,$$$189,$$$200,],[$Touchscreen MP$3$ players,$254,224,204,],[$Audio mixers,$320,178,194,],[$Audio stands,$198,104,86,],[$Video equipment:,,,,$],[$Televisions$,474,299,254,],[5$GB video cards,$285,184,172,],[$Satellite video recorders,$206,619,648,],[$Car equipment:,$179,146,172,],[$GPS navigators,$164,199,214,],[$Double$-$DIN Car Deck with iPod$/$iPhone Control,,,,$]]$

Required:

Calculate the LCNRV for the:

a$.$ inventory by major group

b$.$ inventory, applied separately to each product.