Question

A train has an odd number of cars. The number of cars is greater than 1 and less than 9. An additional 3 cars are attached to the train during rush hour. How many cars could the train have now? List the possible numbers. Tell whether each number is prime or composite. Explain how you know. 1) 3 (Composite) 2) 5 (Prime) 3) 7 (Prime)

Answer 1

After 3 additional cars are attached to the train, it could have 6, 8, or 10 cars. All of these numbers are composite because they have more than two divisors.

Step-by-step explanation:

The question is asking for the possible number of cars the train could have after an additional 3 cars are attached during rush hour. If the train initially has an odd number of cars greater than 1 and less than 9, it could have 3, 5, or 7 cars. If we add 3 more cars to each of these, the train could now have 6, 8, or 10 cars, respectively. Number 6 is divisible by 1, 2, 3, and 6, so it's a composite number. Number 8 is divisible by 1, 2, 4, and 8, so it's a composite number. Number 10 is divisible by 1, 2, 5, and 10, so it's a composite number. None of these are prime numbers (which are only divisible by 1 and itself) so all the possible number of cars the train could have now are composite numbers.

Learn more about Prime and Composite Numbers