[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;


place an f after the numerical value to cast literals as floats (d)s for doubles which is the default.

1 (int)
1.5 (double)
1.5f (float)
1.5d (double)