Question

Dakota runs a half-marathon every 6 weeks, and Madison runs a half-marathon every 15 weeks. If they start now, in how many weeks will they again be running a half marathon at the same time?

Answer 1

30 weeks. You continue to find the factors of each number and find one that’s the same.

6, 12, 18, 24, 30
15, 30

Both lines have the 30 in common. So it’ll take 30 weeks until they run a half- marathon together

Answer 2

30 weeks

Explanation:

Given : Dakota runs a half-marathon every 6 weeks,

Madison runs a half-marathon every 15 weeks

To Find : . If they start now, in how many weeks will they again be running a half marathon at the same time?

Solution :

Since Dakota runs a half-marathon every 6 weeks, Madison runs a half-marathon every 15 weeks

So, to calculate If they start now, in how many weeks will they again be running a half marathon at the same time

We will take the LCM (lowest common factor) of 6 and 15

3 | 6,15

2 | 2,5

5 | 1,5

| 1,1

LCM = 3*2*5 =30

The LCM of 6 and 15 is 30

So, If they start now, in 30 weeks they will again be running a half marathon at the same time