[Beginner] Using Random.Range in initial game object position

I would like a game object to essentially spawn in with a random y value initially, I'm getting an error that states that it can't "convert the double expression to type float." None of my ideas of what's going on have worked, and I can't find the solution with the Scripting API. There's probably a really obvious error, can anybody help?

using UnityEngine; using System.Collections;

public class Upward : MonoBehaviour {

 Vector3 velocity = Vector3.zero;
 public Vector3 AntiGravity;
 float RandomInt = Random.Range(-0.755f, 0.755f);

 // Use this for initialization
 void Start () {
     transform.position = new Vector3(RandomInt,-3.4,-1.0);
 }
 
 // Update is called once per frame
 void Update () {
     if (transform.position.y <= 3.35) {
         velocity -= AntiGravity * Time.deltaTime;
         transform.position -= velocity * Time.deltaTime;
     }
 }

}