Bunuel wrote:
A restaurant menu has several options for tacos. There are 3 types of shells, 4 types of meat, 3 types of cheese, and 5 types of salsa. How many distinct tacos can be ordered assuming that any order contains exactly one of each of the above choices?
A. 60
B. 90
C. 120
D. 150
E. 180
Take the task of building a taco and break it into
stages.
Stage 1: Select a type of shell
Since there are three types of shells to choose from, we can complete stage 1 in
3 ways
Stage 2: Select a type of meat
Since there are four types of meat to choose from, we can complete stage 2 in
4 ways
Stage 3: Select a type of cheese
Since there are three types of cheese to choose from, we can complete this stage in
3 ways
Stage 4: Select type of salsa
Since there are 5 types of salsa to choose from, we can complete this stage in
5 ways
By the Fundamental Counting Principle (FCP), we can complete all 4 stages (and thus build a taco) in
(3)(4)(3)(5) ways (= 180 ways)
Answer: E
Note: the FCP can be used to solve the MAJORITY of counting questions on the GMAT. So, be sure to learn it.
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