Q. A lock has a code of 3 numbers from 1 to 20 . If no numbers in the code are allowed to repeat, how many different codes could be made?Answer:
Permutation Calculation: To solve this problem, we need to calculate the number of ways to choose 3 different numbers from 20 without repetition. This is a permutation problem because the order of the numbers matters for the lock code.Calculation: The first number can be any of the 20 numbers. For the second number, we have 19 options (since we can't repeat the first number). For the third number, we have 18 options (since we can't repeat the first or second numbers).So the total number of different codes is 20×19×18.
Total Number Calculation: Now we perform the multiplication to find the total number of different codes.Calculation: 20×19×18=6840
More problems from Compound events: find the number of outcomes