In an opaque bottle, there are 4 glass balls of the same shape and size in four colors: green, pink, black and white. Touch a ball each time, and put it back after touching, a total of 60 touches. How many times is it possible to touch the white ball?
在一个不透明的瓶子里装着绿、粉、黑、白四种颜色且形状大小相同的4个玻璃球．每次摸一个球，摸完后放回，共摸60次．可能摸到多少次白球？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">60 * (1/4)</gadget>
<output>15</output>

<result>15</result>