Bunuel wrote:
Shipment --- No. of Defective Chips/shipment --- Total Chips in shipment
S1 ---------------------- 2 ------------------------------------------ 5,000
S2 ---------------------- 5 ------------------- ---------------------- 12,000
S3 ---------------------- 6 ------------------------------------------ 18,000
S4 ---------------------- 4 ------------------------------------------ 16,000
A computer chip manufacturer expects the ratio of 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, and S4 combined, as shown in the table above. What’s the expected number of defective chips in a shipment of 60,000 chips?
A. 14
B. 20
C. 22
D. 24
E. 25
Set up equation: \(\frac{x}{60,000}=\frac{2+5+6+4}{5,000+12,000+18,000+16,000}\) --> \(x=20\);
Or: \(2+5+6+4=17\) defective chips in \(5,000+12,000+18,000+16,000=51,000\) chips, so \(\frac{17}{51,000}=\frac{1}{3,000}\): 1 in 3,000. So, expected number of defective chips in a shipment of 60,000 chips is \(\frac{60,000}{3,000}=20\).
Answer: B.
HI..Thanx Buneul....but are we not supposed to add the ratios as 2/5000 + 5/12000 + 6/18000 + 4/16000 thereby giving 7 defectives in 5000...WHAT PART OF THE PROB ACTUALLY INDICATES THAT WE NEED TO ADD THE DEFECTIVES DIVIDED BY OTAL SHIPMENTS.
PL HELP....