420 MP3 players are likely to be defected.
First you would want to do 3000/50 for how any groups of 50 & your answer would be 60
Second you would do 60 times 7 to find the number of defective MP3 players
7 out of 50 are likely to be defective
Multiply by total no. of MP3 players
x= cost per bracelet
number of bracelets * x + shipping charge = total cost