If statement unexpectedly changing value.

The update method is supposed to create a zombie for my game every 10 seconds. I just tried to add a random element to it so that it doesn't spawn every time, just randomly. The problem is that the random variable that I created is being changed to less than or equal to one, making it not random at all.

I don't understand why this is happening, I have code just like this all throughout my program and it works just find everywhere except for here. I understand that for some reason it isn't being read as conditional but I have no idea why, it has always worked for me. What am I doing wrong? I am sure that it must be something simple.

I added the whole Update method for reference, but the part that I am talking about is the first part of the if statement, the other stuff doesn't really matter. The variable of random is declared just above it.

 void Update () {
     float random = Random.Range(0f, numberOfSpawners);
     int variable = Mathf.RoundToInt (Time.realtimeSinceStartup % spawnRate);
     if (random <=1 && variable == 0f && !alreadySpawned) {
         LevelControl();
         spawnCount++;
         spawnRate -= .1f;
         GameObject spawnedZombie = Instantiate(zombie, transform.position, Quaternion.identity) as GameObject;
         spawnedZombie.transform.parent = gameObject.transform;
         alreadySpawned = true;
     } 
     else if (variable != 0f  && alreadySpawned){
         alreadySpawned = false;
     }
 }