There is a box of Go. Black and white pieces are mixed together. There are 150 black pieces and 150 white pieces each. What is the probability of drawing white pieces from the middle?
有一盒围棋，黑子和白子混在了一块，黑棋和白棋各有150颗，那么从中间摸出白子的可能性的大小是多少．
<gadget id="calculator">150 + 150</gadget>
<output>300</output>

<gadget id="calculator">150 / 300</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>