Wait Random Amount of Seconds?

Hello, does anyone know how to make a script where the object does something then waits randomly between ex. 3-6 seconds before doing something else?
I know you can use random range, but I don’t know how to use it for time.

void Start ()
{
StartCoroutine (waiter());
}

IEnumerator waiter()
	{
		int wait_time = Random.Range (0, 50);
		yield return new WaitForSeconds (wait_time);
		print ("I waited for "+ wait_time + "sec");
	}

Use a coroutine.

Unity 2020.3 random conflicts with using System;

Comment //using System;

or UnityEngine.Random.Range();