This Exam P sample reference tests Contingency Tables. Express the four portfolio cells using one male-nonsmoker count and the unknown female-smoker count. The stated total and row differences reduce to 100=2y, so there are 50 female-smoker policies and choice A.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
BThis reports the intermediate difference 100 from the equation 100=2y and omits division by two.
CThis subtracts the overall male-female excess from the smoker total, 350-150=200, but ignores the opposite 100-policy nonsmoker imbalance.
DThis subtracts the nonsmoker difference directly from the smoker total, 350-100=250. Both row differences must be combined before splitting the smoker total.
EAfter the correct female-smoker count is 50, the male-smoker count is 350-50=300. This choice reports the complementary smoker cell.
Original practice · fully worked
Original variant: premium-kit production count
A workshop assembles 96 sensor kits, each either standard or premium. A standard kit uses two control chips, while a premium kit uses five. The day's completed kits use 330 control chips in total. Calculate the number of premium kits assembled.
A 32
B 46
C 50
D 64
E 110
Variant answer in brief
Let S and P be the standard and premium counts. Subtracting twice the total-kit equation from the chip equation leaves 3P=138, so P=46 and choice B.
Setup
Setup
Translate the kit and chip totals into two equations.
S+P=96
2S+5P=330
Model
Model
Remove the two-chip baseline used by every kit.
2S+2P=192
(2S+5P)−(2S+2P)=330−192
Compute
Compute
The remaining chips are the three-chip premium increments.
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