We want to find the lowest common multiple of 3 numbers.
We will see that the 300th caller will get the 3 prizes.
Ok, we know that:
- each 15th caller gets $15.
- each 25th caller gets $25.
- each 100th caller gets free concert tickets.
We want to see the first time that the 3 prizes will be given at the same time (at the same caller).
This will happen for the lowest common multiple of 15, 25 and 100
Now, to find the lowest common multiple we can use brute force, this is, writing all the multiples of the 3 numbers and watching which one is the first to appear in the 3 lists, but here we can do another thing.
One of the numbers is 100, so its multiples are:
100, 200, 300.
And we know that with 25 we can make all of these numbers:
25*4 = 100
25*8 = 200
25*12 = 300
So all the multiples of 100 are also multiples of 25.
Then we just need to find the first common multiple between 100 and 15.
To get this, we can decompose both numbers as a product of primes:
15 = 3*5
100 = 10*10 = 2*5*2*5
Now we multiply these, but if there is some factor that appears in both numbers we remove it (only from one).
For example, here we can see that the factor 5 appears in both numbers, so we need to remove one of the fives in the product.
We will get:
(3*5)*(2*5*2) = 300
So the lowest common multiple is 300.
This means that the 300th caller will get the 3 prizes.
If you want to learn more, you can read:
https://brainly.com/question/11433107
