help

[princessss]

shipment number of defective chips total number of chips in shipment
S1 2 5000
S2 5 12000
S3 6 18000
S4 4 16000

A computer chip manufacturer expects the ratio od the number of defective chips to the total number of chips in all future shipments to equal the corresponding ratio for shipments S1,S2,S3 ans S4 combined, as shown in the table above. What is the expected number of defective chips in a shipment of 60000 chips?

The correct answer is 20 but I don't know how to get it, I do something wrong since I always get 22 as a result. Can anyone help me with this?

[kmittal82]

#total shipments = 5000+12000+18000+16000 = 51000
#defective = 2+5+6+4 = 17

To keep the ratios equal, let there be x defective components out of 60000

17/51000 = x/60000

=> x = 17x60 / 51 = 20

[princessss]

Oh that's easy.. I was doing such a stupid carless mistake :-/ thanks for the help