SQL makes decision for you - strange

I ran into a strange MSSQL behaviour.

I wanted to do some calculation and output it in my application like this:

Declare @aFlaot float

set @aFlaot = 3*1/2

select @aFlaot aFlaot

From above I was expecting a float value as I was storing it in a float type variable but it was returning 1 ( as an integer)

And when I tried following I got back right value with correct decimals

Ex 1)

set @aFlaot = 3*1.0/2

select @aFlaot aFlaot

Returned 1.5 (as expected)

Ex 2)

declare @aVal float
set @aVal = 1

set @aFlaot = 3*@aVal/2

select @aFlaot aFlaot

Returned 1.5 (as expected)

What I understand is SQL decides on the basis of values you are using in your calculation not the container type you are using.