junior 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
We need to first determine the ratio of the defective chips to the total number of chips for shipments S1, S2, S3, and S4.
Defective Chips = 2 + 5 + 6 + 4 = 17 chips
Total Chips = 5,000 + 12,000 + 18,000 + 16,000 = 51,000
Thus the ratio of defective chips to total chips is 17/51,000 = 1/3000. We interpret this ratio as: we would expect 1 defective chip out of every 3,000 chips in the shipment.
To determine the number of defective chips in a shipment of 60,000 chips we can use the following proportion, in which x is the expected number of defective chips in the shipment of 60,000 chips:
1/3,000 = x/60,000
60,000 = 3,000x
x = 20
Answer: B