Question

Good afternoon mam/sir

I am Harshita and my query is:

Aarushi is helping her father plant trees to create a border around the backyard. Aarushi plants a tree every 25minutes and her father plants a tree every 15minutes. If they started together, how long will it be before they would finish planting a tree at the same time.

Thank you

Answer 1

Here Aarushi plants a tree every 25 minutes

25,50,75,100.....
This the times at which Aarushi plant trees.

Her father plants a tree every 15 minutes

15,30,45,60,75,90.......
These are the times at which her father plant trees.

Looking at the multiples of 15 and 25we can see that at the 75th minute they both plant a tree.

The answer can also be got by taking the LCM of 15 and 25.
So the answer is 75.