there are 15 slate rocks, 20 pumice rocks, and 10 granite rocks randomly distributed in a certain field. if 2 rocks are to be chosen at random and without replacement, what is the probability that both rocks will be slate rocks?  Choose the correct choice from the following options:  A) 1 / 3  B) 7 / 22  C) 1 / 9  D) 7 / 66  E) 2 / 45
<gadget id="calculator">15 + 20</gadget>
<output>35</output>

<gadget id="calculator">35 + 10</gadget>
<output>45</output>

<gadget id="calculator">15 / 45</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">45 - 1</gadget>
<output>44</output>

<gadget id="calculator">14 / 44</gadget>
<output>7/22 = around 0.318182</output>

<gadget id="calculator">(1/3) * (7/22)</gadget>
<output>7/66 = around 0.106061</output>

<result>D</result>
there are 15 slate rocks, 20 pumice rocks, and 10 granite rocks randomly distributed in a certain field. if 2 rocks are to be chosen at random and without replacement, what is the probability that both rocks will be slate rocks?
multiply(divide(15, add(add(15, 20), 10)), divide(subtract(15, const_1), subtract(add(add(15, 20), 10), const_1)))
"total no of rocks = 45 probability of choosing 1 st slate rock = 15 / 45 probability of choosing 2 nd slate rock = 14 / 44 ( without replacement ) so combined probability = 15 / 45 * 14 / 44 = 7 / 66 so , answer d ."