SOLUTION: Please show me how to solve this problem " how many numbers are there between 1 and 150 inclusive which are divisible by 5 and leave a remainder of 2 when you divide them by 3?"

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Question 1011715: Please show me how to solve this problem
" how many numbers are there between 1 and 150 inclusive which are divisible by 5 and leave a remainder of 2 when you divide them by 3?"
Thanks

Answer by mathmate(429)   (Show Source): You can put this solution on YOUR website!

Question:
How many numbers are there between 1 and 150 inclusive which are divisible by 5 and leave a remainder of 2 when you divide them by 3?

Solution:
The number of multiples of 5 between 1 and 150 is floor(150/5)=30
where floor(x) is the greatest integer that does not exceed x.

However, question requires that these multiples must leave a remainder of 2 when divided by 3. The smallest number that satisfies this is 5, the next one is 5+(5*3)=20, where 5*3 is the product of the two factors 3 and 5. This continues as 5+(5*3)n where n is an integer, giving 5,20,35,.... as possible candidates.

This will allow you to find the number of candidates required by the question. Since you asked for the method to find it, I will leave it to you to complete the solution.

For more information, google "Chinese remainder theorem" for more explanations and examples.


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